A method for increasing the efficiency of additive drag reduction by establishing a drag-reducing viscoelastic coating on a surface. The method includes mixing a polymer into a concentrated solution that has approximately the same density as a fluid flowing over the surface, ejecting the mixture/solution into the flowing fluid in a manner such that a coating of polymer, which initially grows thicker with time, is adsorbed onto the surface, and reducing the ejection rate of the first fluid such that the coating of polymer then grows thinner with time. These steps may be repeated so that a desired minimum coating thickness is maintained over an extended period of time. The method reduces the polymer expenditure rate for a given drag reduction. Moreover, the produced viscoelastic coating impedes the attachment and growth of drag-producing natural organisms and may be applied without “down-time” (e.g., while underway).

Interest in compliant coatings for marine vehicles dates to the mid-1960s, when Max O. Kramer studied compliant coatings as a means to reduce drag by extending the laminar flow region in a boundary layer [Kramer, M. O., "Means and Method for Stabilizing Laminar Boundary Layer Flow," U.S. Pat. No. 3,161,385, which issued 15 Dec. 1964; and Kramer, Max Otto, "Means and Method for Stabilizing Laminar Boundary Layer Flow," U.S. Pat. No. 3,585,953, which issued 22 Jun. 1971]. Kramer suggested that surface coatings that successfully mimic the skin of a dolphin had the potential to reduce the friction component of the drag of a marine vessel. A successful demonstration was conducted in Long Beach Harbor under the sponsorship of the U.S. Navy Office of Naval Research [Kramer, M. O., "Boundary Layer Control by 'Artificial Dolphin Coating'," Naval Engineers Journal 89(5): 41-45, 1977]. Since that time, there has been little success by U.S. researchers to duplicate that work. However, through the 1970s and 1980s, drag reduction work on coatings, sponsored by the Soviet Navy, was conducted primarily in Kiev, Ukraine and Novosibirsk, Russia. This work, pioneered by L. F. Kozlov and Victor V. Babenko, at the Institute of Hydromechanics in Kiev, Ukraine, produced a series of Soviet Inventors Certificates [Soviet Certificates 1413286, 1483538, 1597866, 1802672]. These Soviet efforts differ from Kramer's in that they are also intended to reduce the level of turbulence in the boundary layer rather than just extend the region of laminar flow. Some coatings were integrated with polymer additives to produce a system that was more effective than either technique alone. Babenko et al. were among the early researchers to recognize the potential of these viscoelastic coatings both alone and in combination with other techniques. The Kiev team was able to identify specific characteristics of a successful coating that had not been specified by Kramer in the details of his earlier effort. It became apparent from the design of these coatings that an important feature is anisotropy in the direction of flow.
Most of the viscoelastic coatings tested in the United States were not successful and some actually increased the drag. After Kramer, the approach of U.S. researchers was to try a range of available coating materials. Not until May and Voropayev [May, C. L. et al., "Design of Viscoelastic Coatings to Reduce Turbulent Friction Drag," U.S. Pat. No. 6,516,652 B1, which issued 11 Feb. 2003] was there an effort to carefully select the properties of the viscoelastic coating considering the parameters of the adjacent turbulent boundary layer. With this approach, unfavorable conditions that had plagued U.S. researchers, such as "static divergence," dynamic roughness, and waves on the coating traveling counter to the flow, [Hansen, R. J. and Hunston, D. L., "Fluid-property Effects on Flow-generated Waves on a Compliant Surface," J. Fluid Mechanics, v. 133, 161-177, 1983] were avoided. May and Voropayev taught that the material properties of the coating should be matched to adsorb the pulsations of the turbulent boundary layer normal to the surface and that the resulting response must be 90 degrees out of phase and in the direction of flow. Following that approach, they identified a number of characteristics necessary for a viscoelastic coating to be successful. First, they reiterated Babenko's teaching that the coating must be anisotropic in the direction of flow. Second, May and Voropayev also taught that any turbulence-generated deformations on the surface of the coating must not exceed the height of the viscous sublayer. Third, they taught that improperly formed transverse coating edges could result in the reflection of turbulence-produced waves in the coating (i.e., edge effects) that would degrade the effectiveness of the coating. Fourth, they taught that the coating density should be approximately the density of the fluid flowing over the coating.
Even when properly posed, the coatings are fragile and can rupture, thereby degrading their effectiveness. In general, the coatings were of sufficient complexity and high cost that their application apparently has been limited to military submarines. The coatings are usually on the order of one to ten centimeters thick, making them heavy and difficult to install. For these reasons, commercial application has yet to become practicable.
There are other categories of coatings that are commercially available and claim drag reduction [Gilman, Thomas H., "Methods of Applying a Hydrophilic Coating to a Substrate, and Substrates Having a Hydrophilic Coating," Pub. No. US 2007/0184275 A1 published 9 Aug. 2007, and Dietz, Timothy M. et al., "Drag Reduction Article and Method of Use," Pub. No. US 2004/0126541 A1 published 1 Jul. 2004], or the ability to inhibit marine fouling [Hamilton, Willard Chalson et al., "Hydrophilic Fouling-release Coatings and Uses Thereof," Pub. No. US 2007/0258940 A1 published 8 Nov. 2007], but these are not viscoelastic. Others include hydrophilic bottom coatings for boats, such as SEA-SLIDE™ and water ablative painted coatings that release polymer into the boundary layer [Supcoe et al., U.S. Pat. No. 5,488,076, which issued 30 Jan. 1996]. Also, adhesive-backed vinyl microgrooved surfaces (referred to as riblets), when clean of any fouling, are known to reduce drag. Such microgrooves order and stabilize the longitudinal flow structures near the surface. However, these coatings each perform only a single function (e.g., biofouling inhibition, polymer release, or provide a surface structure) and require special surface application when the hull is dry (i.e., out of the water). Thus, the vessel must be removed from service (i.e., drydocked) for re-application. More recently there have been a number of efforts to use emerging nanotechnology to produce turbulence-interactive surfaces in order to reduce friction drag [Karniadakis, George Em et al., "Method and Apparatus for Reducing Turbulent Drag," U.S. Pat. No. 6,520,455 B2, which issued 18 Feb. 2003; Nosenchuck, Daniel M. et al., "Electromagnetic Device and Method for Boundary Layer Control," U.S. Pat. No. 5,320,309, which issued 14 Jun. 1994; and Nosenchuck, Daniel M. et al., "Multiple Electromagnetic Tiles for Boundary Layer Control," U.S. Pat. No. 5,437,421, which issued 1 Aug. 1995], but these systems are complex, require advanced control systems, and can consume significant levels of energy.
Hence, there is a need for a simple, environment-tolerant, and cost-effective drag-reducing coating, which can be exploited so as to increase the performance and operational efficiency of vessels moving through water (as well as liquids moving through pipes or ducts) and can be applied without large maintenance expenses and/or drydock requirements.
Experimentally, friction reduction has been more reliably achieved by the introduction of additives into the boundary layer flow. The most common additives are aqueous solutions of long chain polymers [Hoyt, J. W. and Fabula, A. G., "Frictional Resistance in Towing Tanks," Proc. 10th Intern. Towing Tank Conf., Teddington, 1963; Hoyt, J. W., "Fluid-Flow Friction Reduction," NURDC, May 5, 1969; and Hoyt, J. W., "Drag Reduction by Polymers and Surfactants," in Viscous Drag Reduction in Boundary Layers, edited by D. M. Bushnell and J. N. Hefner, Vol. 123, 413-429, 1990]. A number of techniques have been developed to select, prepare, and stabilize polymer drag-reducing solutions [Bock, Jan et al., "Drag Reduction Agent," U.S. Pat. No. 4,585,810, which was issued 29 Apr. 1986; Labude, Katrina M. et al., "Drag-reducing Polymer Suspensions," Pub. No. US 2003/0187123 A1 published 2 Oct. 2003; Johnston, Ray L. et al., "Method for Manufacturing Drag-reducing Polymer Suspensions," Pub. No. US 2003/0065055 A1 published 3 Apr. 2003; Martin, Thomas J. et al., "Stabilized Polymer Drag Reducing Agent Slurries," U.S. Pat. No. 7,256,224 B2, which was issued 14 Aug. 2007; Martin, Thomas J., "Stabilized and Freeze-protected Polymer Drag Reducing Agent Suspensions," Pub. No. US 2007/0205392 A1 published 6 Sep. 2007; and Bassett, David Robinson et al., "Processes for Preparing Aqueous Polymer Emulsions," Pub. No. US 2002/0045703 A1 published 18 Apr. 2002]. Other techniques have been developed to enhance the coating property of polymers [Trippe, J. C. et al., "High Molecular Weight Polymer Additive for Coating and Protective Products," Pub. No. US 2002/0106454 A1 published 8 Aug. 2002], for the purpose of strengthening fibers and sealing surfaces as opposed to enhancing drag reduction.
Other drag-reducing additives include: surfactant-based solutions in which micelles have been formed [Gyr, A. and Bewersdorff, H. W., "Drag Reduction of Turbulent Flows by Additives," Kluwer Academic Publ., (ISBN 0-7923-3485-X), 1995]; fibrous materials such as asbestos or nylon [Lee, W. K. et al., "Turbulent Drag Reduction in Polymeric Solutions Containing Suspended Fibers," AI Ch E J., 20 (1), 128-133, January 1974; and Sharma, R. S. et al., "Drag Reduction by Center-line Injection of Fibers in a Polymeric Solution," Chem. Eng. J., 18, 73-79, 1979], and small gas bubbles, referred to as "microbubbles" [Merkle, C. L. and Deutsch, S., "Drag Reduction in Liquid Boundary Layers by Gas Injection," in Viscous Drag Reduction in Boundary Layers, edited by D. M. Bushnell and J. N. Hefner, Vol. 123, 351-410, 1990]. While each of these techniques was successfully demonstrated in the laboratory, their practicability was limited by several factors. For microbubbles, the limitations relate to their migration away from the near-wall region of the boundary layer where they are effective as well as their coalescence into larger-scale bubbles, which are less effective in reducing drag. Except for a limited set of ejector geometries, polymers and other additives can be rapidly diffused away from the region where they are effective, thereby requiring very large expenditure rates to maintain effective levels of additive concentration near the wall [Vdovin, A. V. and Smol'yakov A. V., "Turbulent Diffusion of Polymers in a Boundary Layer," Journal of Applied Mechanics and Technical Physics, 22 (4), 526-531, 1981]. Also, the polymers had to be premixed and carried as a slurry to ensure they were properly mixed and hydrated. Because of the very high expenditure rates required with traditional ejection techniques [see, for example, Winkel, E. S. et al., "Friction Drag Reduction at High Reynolds Numbers with Wall Injected Polymer Solutions," 26th Symposium of Naval Hydrodynamics, Rome, Italy, 2006], large volumes of slurry are expected to be expended in a matter of hours and the application of polymers appeared to be limited to military vessels in which a quick burst of speed might be useful.
In addition to reducing friction drag when used separately, the ejection of fibers, such as asbestos or nylon, also enhance the performance of polymer ejection reduction [Lee, W. K. et al., "Turbulent Drag Reduction in Polymeric Solutions Containing Suspended Fibers," AI Ch E J., 20 (1), 128-133, January 1974; and Sharma, R. S. et al., "Drag Reduction by Center-line Injection of Fibers in a Polymeric Solution," Chem. Eng. J., 18, 73-79, 1979]. Lee et al. reported that the quantity of fibers, which alone produced about 15 percent reduction in friction drag, produced over 60 percent friction reduction when combined with the quantity of polymer that alone produced only about 36 percent skin friction reduction. Sharma et al. later confirmed the generality of the enhanced drag-reduction performance of combined polymer and fiber systems. The opportunity to exploit that synergism has been elusive because of limitations on marine and industrial applications of fibers. Such fibers are known to be hazardous to handle and most are considered to be long-term pollutants. On the other hand, microbubbles and polymers break down into air for the former and natural compounds such as carbon dioxide and water for the latter.
There are other examples of synergism between various drag-reducing techniques. For example, it has been known that the proper combination of polymer ejection and microbubble ejection, as with fibers and polymer, can produce higher levels of drag reduction than the sum of individual performance levels [Semenov, B. N. et al., "Combined Effect of Small Amounts of Polymers Added to a Flow and of Surface Pliability on Turbulent Friction," Seriya Tekhnichesikh Nauk: 89-94, 1984; Amirov, A. I. et al., "Experiments on Turbulent Drag Reduction by Joint Use of Compliant Coatings, Gas Microbubbles and Polymer Additives," Abstr. 9th European Drag Reduction Meeting, Ravello-Napoli, 1995; and Deutsch, S. et al., "Combined Polymer and Microbubble Drag Reduction on a Large Flat Plate," Journal of Fluid Mechanics 556: 309-327, 2006]. Also, Kozlov, Babenko, and Semenov reported that the efficiency of polymer ejection, when used with even an individually poor performing viscoelastic coating, could be significantly enhanced. Similarly, it has been shown that the combined action of riblets and polymer additives yield a level of drag reduction that is greater than the separate effects [Koury, E. and Virk, P. S., "Drag Reduction by Polymer Solutions in Riblet-Lined Pipes," Abstracts 8th European Drag Reduction Working Meeting, Lausanne, Switzerland 1993]. Thus, if the negative environmental effects of fibers and the difficulties associated with the development and maintenance of a drag-reducing viscoelastic coating could be overcome, these techniques not only would offer a practical method of modest friction drag reduction, but also when used in combination with the Toms Effect (the ejection of a dilute aqueous solution of polymer), it is apparent that the integrated system would be both more effective and more efficient than polymer ejection by itself.
Polymers used in drag reduction, such as polyethylene oxide (PEO), are known to form adsorption entanglement layers while in contact with or flowing over a surface [Barham, P. et al., "Adsorption-entanglement Layers in Flowing High Molecular Weight Polymer Solutions III. Solution Concentration and Solvent Power," Colloid & Polymer Science, 264(6): 515-521, 1986; Hand, J. H. and Williams, M. C., "The Adsorbed-entangled Layer in Drag Reduction," Chemical Engineering Science, 28: 63-68, 1973; and Kowalski, T., "Turbulence Suppression and Viscous Drag Reduction by Non-Newtonian Additives," Transactions of the Royal Institution of Naval Architects, 207-219, 1968]. The factors that control the formation and growth of adsorption-entanglement layers include the chemical nature of the surface at which the layers form, the polymer solution concentration, the molecular weight of the polymer, the solvent power, the temperature, and the rate of the flow over the surface. Specifically, with increased molecular weight, increased concentration, better solvents, and increased flow rates (e.g., higher vessel speed), the layers formed more rapidly and tended to grow thicker [Barham, P. J., "A Quantitative Model for the Formation of Adsorption-entanglement Layers," Colloid & Polymer Science, 265(7): 584-591, 1987; and Dijt, J. C. et al., "Kinetics of Adsorption and Desorption of Polystyrene on Silica from Decalin," Macromolecules 27: 3207-3218, 1994]. Since an aqueous salt solution is a good solvent for PEO, a rather extended layer can be expected in a saltwater environment [Jones and Richards, "Polymers at Surfaces and Interfaces," Cambridge University Press, 1999]. This phenomenon is well understood in the fields of colloid and polymer science, particularly in the areas of research and industry where the behavior of polymers at surfaces and interfaces are of interest. The early reports by Kowalski (external flow) and Hand and Williams (internal flow) were almost immediately challenged, at least in part by key leaders in the drag reduction community [Kowalski, T., "Turbulence Suppression and Viscous Drag Reduction by Non-Newtonian Additives," Transactions of the Royal Institution of Naval Architects, 207-219, 1968 (see the appended written discussions at pages 216-219 by G. E. Gadd, A. G. Fabula, B. Latto and C. H. Shen); and Gyr, A. and, Mueller A., "The Effect of Wall Absorption on the Toms Effect," Chemical Engineering Science 29: 1057-1060, 1974]. The lack of acceptance of polymer adsorption onto surfaces for external flows can be attributed to several factors. During laboratory tests with scale models or flat plates in water tunnels, the test runs are of short duration, often less than a minute. The short test periods are to ensure that the background level of polymer does not build up and bias the test results. Also, to inhibit any background buildup, the tunnel is run at high speed after the short test periods and often with sufficient levels of chlorine to "degrade" the polymer in solution. Thus, in addition to limiting opportunity for adsorption, the effect of the added chlorine and high-speed flushing of the tunnel would inhibit the adsorption process. Reviews of Kowalski's work overlooked the fact that he had an open rather than a recirculating test facility. Thus, the flow could be continuous with no concern for previously ejected polymer contaminating the incoming flow. Kowalski ran his tests for extended periods without intentionally trying to "flush" his test apparatus. He also conducted tests on a small craft in open water. Second, and also of critical importance, Kowalski was apparently the first to use a very shallow angled (five degrees to the surface) ejector slot. He demonstrated that such a shallow ejection angle greatly reduced the diffusion rate of the ejected polymer away from the surface. The importance of this ejector feature in reducing the diffusion rate was later quantified by Vdovin and Smol'yakov (1978 and 1981). Later at-sea tests were also limited to just two to five minutes in duration. This duration limit of two to five minutes was because of the large expenditure rates required by inefficient ejectors that required very large volumes of polymer slurry. The usual concentration for a slurry was 10,000 wppm (weight parts per million), which equates to just one part polymer to 99 parts water by weight. Thus, the volume of slurry required for just a few minutes of test dictated that individual tests be short in duration if more than a few conditions were to be evaluated. The series of at-sea tests conducted by Moore et al. [Moore, K. J. et al., "Design and Test of a Polymer Drag Reduction System on Sea Flyer," presented at the 26th Symposium on Naval Hydrodynamics, Rome, Italy, 17-22 Sep. 2006] employed an on-demand polymer make-down (mixing and activating, i.e., uncoiling the polymer molecules) system using seawater. This on-demand system, coupled with the Cortana fluidics ejector, reduces the storage volume and expenditure requirements, thus enabling near-continuous testing. Over the course of each day, individual test runs extended over periods of ten to 45 minutes allowing multiple individual tests to be conducted over the course of one day. Hence, unlike water tunnel and previous at-sea tests, low expenditure rates, tangential ejection, and sufficient time provided the conditions necessary for the establishment of adsorption entanglement layers. It is also known that the flow of polymer solution under a varying tangential shear stress will cause deformation of adsorbed PEO layers. Churaev et al. report that the hydrodynamic thickness of the adsorbed layers can be changed by a factor of two or more for shear stress values expected for a 30-knot ship. The changes in thickness are not caused by desorption (a term used in the related literature), which requires an extended time. Under shear stress, the adsorption layers deform quickly but reversibly and the PEO adsorption layers behave as viscoelastic bodies [Churaev, N. V. et al., "Hydrodynamic Thickness and Deformation of Adsorbed Layers of Polyethylene Oxides," Journal of Colloid and Interface Science 169: 300-305, 1995]. The process of deformation has the effect of compressing and consolidating the adsorbed layers. Hence, one can expect the viscoelastic properties of the layers to change as a function of the adjustments in shear stress; that is, the viscoelastic properties will modulate due to the adjustments in vessel speed in terms of both magnitude and frequency of the changes. Also, if gas microbubbles are to be used in combination with polymer ejection and the establishment of adsorption entanglement layers, the presence of microbubbles could result in air being entrained in the layers. If the coating is just being established and gas microbubbles are entrained as the coating is being formed, the density of the coating as well as its viscoelastic properties will be modified. The modification produced by entrained air was observed to degrade the overall drag-reducing performance beginning several minutes after gas ejection was initiated and continued for up to tens of minutes after gas ejection was stopped. However, for more established coatings, system degradation during and after gas ejection was not observed. Thus, relaxing the shear stress on the coatings that are being formed, by measurably slowing or stopping the vessel, can release entrained gases, and returning to speed will again compress and consolidate the coating without reduced entrained materials.
Further, using Fourier transform infrared spectroscopy, it has been shown that, in the presence of a flow field, the backbone of the polymer chain becomes oriented in the direction of the flow, even at low shear rates [Frantz, P. et al., "Orientation of Adsorbed Polymer in Response to Shear Flow," Colloids and Surfaces A: Physicochemical and Engineering Aspects 86: 295-298, 1994]. Thus, the character of the adsorbed viscoelastic layer, when produced in a flow field, is anisotropic in the direction of flow. In general, a large number of long molecules can be bound to the surface. They may form large "loops" that extend out into the solution and are separated by "trains" that are physically adsorbed, as well as long "tails" that trail back into the solution. These tails are sometimes referred to as "brushes," which can become dense as they trail out into the flow field. Thus, as the flow continues, the coating can grow by entanglement of free flowing molecules with previously established molecules having loops and tails.
It is also well known that polyethylene oxide (PEO) surfaces are strongly resistant to protein and other biomolecule adsorptions [Harris, J. M. and Zalipsky, S. (Editors), Poly(ethylene glycol) Chemistry and Biological Applications, ACS Symp. Ser. 680, American Chemical Society, Washington, D.C., 1997]. A film of PEO is used as a surface protector to reduce protein adsorption and cell adhesion in medical implants, biosensors, and diagnostic devices [Biederman, Hynek (Editor), Plasma Polymer Films, Imperial College Press, London, pp. 237-239, 338-340, and 357-361, 2004]. The ability of PEO film to inhibit cell adhesion so as to prevent the formation of microbial slimes that produce drag and allow barnacle and tubeworm macrofouling to occur has been observed by the present inventors.
To produce an anisotropic viscoelastic coating efficiently and effectively, both the concentration of high molecular weight polymer solutions along the wall and in the free stream (having a velocity U∞) should be sufficiently high to ensure a high probability of adsorption entanglement on the wall. Ejection techniques that direct the ejected polymer out into the stream, rather than tangent or nearly tangent to the wall, will enhance diffusion of the polymer away from the near-wall region. [Vdovin, A. V. and Smol'yakov, A. V., "Diffusion of Polymer Solutions in a Turbulent Boundary Layer," Journal of Applied Mechanics and Technical Physics 19 (2), 196-201, 1978; and Vdovin, A. V. and Smol'yakov, A. V., "Turbulent Diffusion of Polymers in a Boundary Layer," Journal of Applied Mechanics and Technical Physics 22 (4), 526-531, 1981]. On the other hand, an ejector that directs the ejected polymer along the vessel wall (i.e., the vessel hull) without introducing unsteadiness will contribute to the suppression of turbulent diffusion and will ensure that high concentrations of the ejected material remain close to the wall, thereby increasing the potential to establish adsorption-entanglement layers. The ability to produce a tangential ejector using straight slot techniques in the past had presented structural, spatial, and fabrication challenges. However, such a shallow angle ejector (about five degrees to the flow surface) has been demonstrated to produce very short-lived (i.e., on the order of minutes) adsorbed layers [Kowalski, T., "Turbulence Suppression and Viscous Drag Reduction by Non-Newtonian Additives," Transactions of the Royal Institution of Naval Architects 207-219, 1968]. Since that test arrangement involved no recirculation but continuous replenishment of the free stream fluid, it is apparent that the observed adsorption was the result of only ejected polymer and not the long-term buildup of an ambient or "background" concentration of polymer in the flow field. More recently, at-sea experiments with the Cortana Corporation fluidics ejector [Moore, K. J. et al., "Method and Apparatus for Increasing the Effectiveness and Efficiency of Multiple Boundary Layer Control Techniques," U.S. Pat. No. 6,357,374 B1, which issued 19 Mar. 2002] demonstrated the feasibility of establishing longer term and operationally practical adsorption entanglement layers on an operational vessel. By ejecting tangentially and avoiding the local increase in turbulence traditionally associated with additive ejection, this ejection technique retards the rapid diffusion of the additive across the boundary layer.
The present inventors have determined that tangential ejection of a concentration Ci of just 1,000 to 1,500 wppm of PEO WSR-310 at flow rates of 5 to 10 times the flow through the viscous sublayer (i.e., Qi=5Qs to 10Qs) is adequate to establish adsorbed layers in the order of tens of minutes. Once the adsorbed coating is established, the expenditure rate (i.e., the product of concentration Ci times the flow rate Qi) could be reduced substantially (namely, by a factor of more than two) relative to the initial rate with an uncoated hull and still achieve the same level of drag reduction. Hence, much more modest quantities of additive now support extended periods of drag reduction. Further, the ability to mix additives, such as polymer, on demand with seawater [Moore, K. J. et al., "Design and Test of a Polymer Drag Reduction System on Sea Flyer," presented at the 26th Symposium on Naval Hydrodynamics, Rome, Italy, 17-22 Sep. 2006] has eliminated the need to carry the additive in fresh-water mixed slurry form and permits the polymer to be mixed and ejected in an aqueous salt solution.
With regard to the environmental impact, the weight expenditure of polymer relative to the weight of fuel saved for a given vessel depends on the amount of drag reduction, the speed of the vessel, and the portion of friction drag relative to total drag. Since the expenditure rate of polymer, with a proper ejector, is linear with speed and the expenditure rate of fuel is approximately cubic with speed, the benefit of polymer drag reduction increases with vessel speed. For well-designed, high-speed vessels operating over 30 to 35 knots, such as large multi-hull ferries, the ratio of fuel saved to polymer expended is on the order of 10:1. When a simple fuel such as octane C8H18 is burned, it can produce a number of noxious gases, water, and of course carbon dioxide (CO2). The oxidation of a kilogram of octane produces just over three kilograms of carbon dioxide. Polymer naturally degrades into water and carbon dioxide. In seawater, because of the presence of salts, the degradation process has been observed to proceed rapidly after just several tens of minutes. However, that process produces only about two kilograms of carbon dioxide for each kilogram of polymer oxidized. Consequently, oxidation of one kilogram of octane can be expected to produce more than 50 percent more carbon dioxide than the oxidation of one kilogram of PEO. Since the ratio of the weight of fuel saved to the weight of polymer expended is on the order of 10, the CO2 emissions that would have been generated by the fuel saved are reduced by a factor of about 15 (i.e., the CO2 emissions would be about 93% the amount they otherwise would have been). Thus, if the overall vessel drag were reduced by 30 percent, this would equate to a roughly a 30% reduction in fuel burned, and thus a reduction of about 28% in CO2 emissions would be realized.

Method to increase the efficiency of polymer drag reduction for marine and industrial applications


A method and a system may automatically compute optimized target resources and identify configurations given discovered source properties and dependencies of machines, while prioritizing performance in the target environment. An algorithm and/or tools for programmatically identifying and locating business application instances in an infrastructure, based on weighted similarity metric may be also provided.

Enterprises are increasingly moving their Information Technology (IT) infrastructures to the Cloud, driven by the promise of low-cost access to ready-to-use, elastic resources. Existing migration approaches typically replicate source resources and configurations on the target site, making it challenging to optimize the resource usage (for reduced cost with same or better performance) or cloud-fit configuration (no misconfiguration) after migration. The responsibility of reconfiguring the target environment after migration is often left to the users, who, as a result, may not reap the benefits of reduced cost and improved performance in the Cloud.
For instance, the promise of elastic, resilient, and flexible Cloud infrastructures, often associated with a pay-per-use model, is driving enterprises to migrate their legacy IT infrastructure. From startups to large enterprises with legacy data centers to government agencies, organizations with data centers of all sizes and requirements are interested in taking advantage of the cost savings and flexibility that the Cloud can offer. The question for enterprises of whether migration to the Cloud is the right strategy is now turning into the question of how to leverage the Cloud's abundance of resources for company benefit.
Existing migration processes typically move a site's source environment to a target environment of the user's choice, with post-configuration and optimization of the target left to the user. As a result, the benefits of a Cloud infrastructure may not reaped by consumers, since the target setup has not been customized to the Cloud environment. Post-configuration and optimization is often associated with high cost, especially for large data centers, due to the hands-on expertise that is required and the time necessary for manual execution of many of these activities.

Resource provisioning planning for enterprise migration and automated application discovery

International Business Machines Corporation


A method for operating a memory includes receiving an input data set, saving a first level error correcting code ECC for the data in the input data set, saving second level ECCs for a plurality of second level groups of the data in the data set, storing the data set in the memory, and testing the data set to determine whether to use the first level ECC or the second level ECCs. The method includes, if the first level ECC is used, storing a flag enabling use of the first level ECC, else if the second level ECCs are used, storing a flag enabling use of the second level ECCs. The method includes storing the second level ECCs in a replacement ECC memory, and storing a pointer indicating locations of the second level ECCs in the replacement ECC memory.

Field of the Invention
The present invention relates to memory devices and systems including error correction code (ECC) logic.
Description of Related Art
Memory technologies used for integrated circuit memories are being developed at smaller and smaller technology nodes, and are being deployed on larger and larger memory arrays on a single integrated circuit. As the technology for memory cells advances, the margins for sensing the data can become tighter. Also, the ability of the memory cells to hold data values in the presence of disturbance of the memory cell state caused by high speed and high volume accesses to the memory cells and to neighboring memory cells can be limited by the tighter margins.
To address issues like those that arise from tighter margins and memory cell disturbance, as these technologies scale in size and density, use of error correcting codes (ECCs) embedded with integrated circuit memory has been developed. However, each memory has limited resources for storing error correcting codes.
Thus, it is desirable to provide a method that efficiently utilizes limited resources available in a memory for ECCs.


In a manufacturing process of a semiconductor device, electroplating and CMP have had a problem of increase in manufacturing costs for forming a wiring. Correspondingly, an opening is formed in a porous insulating film after a mask is formed thereover, and a conductive material containing Ag is dropped into the opening. Further, a first conductive layer is formed by baking the conductive material dropped into the opening by selective irradiation with laser light. Subsequently, a metal film is formed over the entire surface by sputtering, and the mask is removed thereafter to have only the metal film remain over the first conductive layer, thereby forming an embedded wiring layer formed with a stack of the first conductive layer containing Ag and the second conductive layer (metal film).

1. Field of the Invention
The present invention relates to a semiconductor device having an integrated circuit and a method for manufacturing the same. The invention particularly relates to an electronic device having, as a component, a semiconductor element including an embedded wiring.
Note that a semiconductor device in this specification means general devices and apparatuses which can function with the use of semiconductor characteristics; for example, electro-optical devices, semiconductor circuits, and electronic devices are all included in a semiconductor device.
2. Description of the Related Art
In recent years, in the case of forming a multilevel interconnection which includes a plurality of wiring layer in a semiconductor element, irregularities are more significant in upper layers, and the wirings are difficult to be processed. Correspondingly, a wiring material is generally embedded in a wiring opening such as a wiring trench or a hole formed in an insulating film by a wiring formation technology called a damascene process.
A damascene process is a method in which a trench is first formed in an insulating film, the entire surface is covered with a metal material (filling the trench), and the entire surface is polished by CMP (chemical mechanical polishing) or the like to form a metal wiring. The method further including a step of providing a hole below a metal wiring for contact with a metal wiring or a semiconductor region in a lower layer is called a dual damascene process. The dual damascene process includes a step in which, after forming a hole for a connection with a lower layer wiring and a wiring trench are formed, a wiring material is deposited, and the wiring material except the wiring part is removed by CMP.
For a metal wiring using a dual damascene process, copper (Cu) by electroplating is commonly used. In the electroplating, a plating solution or the electric field to be applied is required to be controlled intricately so that copper (Cu) is completely embedded in the connection hole. Further, it is difficult to process copper (Cu) by an etching process using an etchant or an etching gas; therefore, a special CMP method is required for polishing for copper (Cu) processing.
Electroplating and CMP have had a problem of increase in manufacturing costs for forming a wiring.
Further, in order to achieve a high performance semiconductor device that is capable of high speed operation, a structure in which an insulating film having lower dielectric constant is used for the insulating film to be provided with a wiring opening in addition to using a wiring material having lower resistivity than copper (Cu) is further required in the future.
Hence, the present inventors consider using silver nanoparticles for obtaining a wiring formed of silver or an alloy mainly containing silver each having lower resistivity than copper. However, the present inventors found problems that, since a silicon dioxide film or a silicon nitride film which is used for a conventional interlayer insulating film is dense, the area in contact with silver nanoparticles is small and the adhesion is weak.
Further, as for a silicon dioxide film (∈=4.1 to 3.7) which has been used for a conventional interlayer insulating film, the dielectric constant is high; thus, an insulating film having further lower dielectric constant is required.

Semiconductor device and method for manufacturing the same

Semiconductor Energy Laboratory Co., Ltd.


A predictive enhanced maneuverability system providing enhanced timely delivery of vehicle performance selection of chassis, and steering modes for potential predicted safety collisions is disclosed. The primary inputs of the disclosed invention include a determination of the proximity to a preceding vehicle, the density of the surrounding traffic, a forward collision warning alert, and the predictive enhanced maneuverability decision sub-system for vehicle mode selection. The system of the disclosed invention provides a customized vehicle dynamics chassis and steering dynamic mode output, based on a predicted decision about vehicle potential for collision, for improved driver maneuverability and safety. In addition, the disclosed invention provides an improved system and method for incorporating the time dependent headway, forward collision warning alert, and the traffic density for chassis collision-mode embedded decision-making. The predictive enhanced maneuverability decision-module allows vehicle dynamics mode selection to be tailored based on proximity to a potential collision.

Automotive technology capable of delivering automatic vehicle mode adaptation based on the driver, the vehicle, and environmental conditions is a developing area of technology. While variations of adaptive technologies are known, in some known instances the automatic vehicle mode demonstrates adaptive vehicle dynamics and powertrain mode selection from, for example, sporty, normal, and comfort to enhance the overall driving experience.
However, development of adaptive technologies is still in the early stage and other opportunities to augment known adaptive vehicle systems exist. These advancements may be achieved by leveraging predictive sensing and information capabilities on vehicles to cover more scenarios for improved driver convenience and safety.
The challenge is to develop additional methods that can in real-time predict situations to enhance the automotive mode selection for the vehicle. For example, it is beneficial to have a method that would intelligently select the chassis steering and suspension combination for enhanced maneuverability for a predicted potential collision.
Innovative vehicle technologies provide significant opportunities for enhanced adaptive vehicle systems to meet the needs of tailored vehicle performance and customization.

Method and system for predictive vehicle systems performance selection for enhanced maneuverability


A carpet removal or stripping method and system (machine) employs a common dolly. The backside of the dolly member has a plurality of teeth. A motorized winching system is coupled to the front side of the dolly member. A dual purpose safety shield covers the teeth during transportation and serves as a protective screen for the user during carpet removal operation of the invention machine. The winching system automates carpet peeling activity with the dolly member lying backside down during operation, and the teeth provide an anchoring effect. A pull bar removably grasps the subject carpet. A cable is coupled between the winching system and the pull bar. The winching system takes up or pulls the cable and hence the pull bar, such that the carpet is peeled away and separated from the subfloor.

In the flooring industry, carpet is typically installed from 12-foot wide rolls or in one foot square carpet "tiles". The carpet material is glued and/or tacked to the subfloor. It is a laborious task to remove such installed carpeting. There are limited tools for assisting with carpet removal, especially for homeowner use in the residential setting.
There is a motorized tool/machine for removing carpet tiles and other tiles in an industrial setting by National Flooring Equipment of Minneapolis, Mo. Further National Flooring Equipment provides an industrial carpet lifting or pulling machine that utilizes a ¾ horsepower electric motor.
Other carpet removal tools are not automated or motorized such as in U.S. Pat. No. 5,505,433 to Carmichael et al.


A thin film magnetic head includes a magnetoresistive element portion movable over and relative to a magnetic recording medium for reading information stored therein, upper and lower shielding layers disposed with the magnetoresistive element portion therebetween for magnetically shielding the magnetoresistive element portion, and upper and lower gap insulative layers respectively interposed between the upper shielding layer and the magnetoresistive element portion and between the lower shielding layer and the magnetoresistive element portion. Each of the upper and lower gap insulative layers includes a hydrogen-incorporated film. The upper gap insulative layer has an increased hydrogen content and a reduced internal stress relative to the lower gap insulative layer.

1. Field of the Invention
The present invention relates to a thin film magnetic head which can be employed for information processing devices such as personal computers or workstations, and which has a magnetoresistive element portion that moves over and relative to a magnetic writing or recording medium (hereinafter referred to as a recording medium), such as a hard or floppy disk, to read stored information.
2. Description of Related Art
Thin film magnetic heads have been conventionally employed in effecting high density recording of information onto the recording medium. One example of such thin film magnetic heads is described in Japanese Patent Laying-open No. Hei 6-223331 (1994). FIG. 7 is a schematic cross-sectional view of such a prior art magnetic head.
As shown in FIG. 7, the prior art thin film magnetic head has a substrate 1 on which an insulative layer 20 formed of diamond-like carbon (hereinafter referred to as DLC), a shielding layer 3, an insulative layer 21 formed of DLC, a magnetoresistive element portion (hereinafter referred to as an MR element layer 5), lead layers 6-A and 6-B, an insulative layer 22 formed of DLC, and a shielding layer 8 are stacked in such a consecutive order.
FIG. 8 is a partly enlarged view of the MR element layer 5 and lead layers 6-A and 6-B in FIG. 7.
Referring now to FIGS. 7 and 8, the lead layers 6-A and 6-B are coupled to opposite ends of the MR element layer 5. The MR element layer 5 has a nonmagnetic interlayer 11 sandwiched between a magnetoresistive layer 12 and a soft magnetic layer 10 which is closest of the three to the substrate 1. The soft magnetic layer 10 is a film for applying a bias electric field to the magnetoresistive layer 12. The nonmagnetic interlayer 11 is a film for magnetically isolating the soft magnetic layer 10 from the magnetoresistive layer 12 which is a film for converting magnetic flux changes to signals.
Each of the lead layers 6-A and 6-B has an antiferromagnetic bias layer 13 on which an adherence enhancing layer 14 and a conductive lead layer 15 are consecutively stacked. The lead layers 6-A and 6-B define an operational region 6-C therebetween.
When desired to read information stored in the recording medium using the above-described thin film magnetic head, a rated current is applied to the lead layer 6-A to allow the rated current to flow therefrom through the MR element layer 5 to the lead layer 6-B. The current flowing into the MR element layer 5 produces an electric field perpendicular to a direction of the current flow, inducing magnetic fields in the magnetoresistive layer 12 as well as the soft magnetic layer 10, so that the magnetoresistive layer 12 is biased in the direction of the current flow through a coupling effect.
When subjected to an external magnetic field while in such a biased state, the magnetoresistive layer 12 changes in its resistance with varying magnetic field. The output can be obtained by processing the resistance changes as signals.
However, DLC layers are generally high in internal stress, particularly in compressive stress. Due to the action of this compressive stress, a tensile force acts on a body adhered to the DLC.
In the above-described thin film magnetic head, the lead layers 6-A and 6-B, as well as the MR element layer 5, are sandwiched between the insulative layers 21 and 22. Accordingly, the compressive forces generated in the insulative layers 21 and 22 are likely to act to deform the MR element layer 5, leading to failure of obtaining desired electrical characteristics and, as a consequence, loss of reliability.
Furthermore, forming the insulative layers having a high compressive stress directly on the shielding layers, as described above, is very likely to cause upper layers including the insulative layers to be delaminated from the substrate when subjected to the action of compressive forces in the insulative layers.

Thin film magnetic head including adhesion enhancing interlayers, and upper and lower gap insulative layers having different hydrogen contents and internal stress states


The optical driving device according to the present invention includes a holder for holding a plurality of optical each of which focuses on an optical disk a light beam outputted from a light source, focusing coils, and tracking coils; a plurality of elastic support members for supporting the holder so as to be movable in an approximately radial direction of the optical disk and in an approximately perpendicular direction to the optical disk; and a base for holding inner yokes placed inside the holder, and magnets that generate magnetic fields with respect to the focusing coils and to the tracking coils; as for the optical driving device, the top face of the holder has a closed structure over the inner yokes.

In recent years, there developed are various kinds of optical disks each of which is different in the recording density, a cover-layer thickness or the like; for example there are a CD (compact disc) whose usable wavelength is in the vicinity of 780 nm, a DVD (digital versatile disc) whose usable wavelength is in the vicinity of 660 nm, a BD (Blu-ray disc) and an HD-DVD (high definition DVD) whose usable wavelength is in the vicinity of 405 nm, and the like. In such an optical disk apparatus adapted to a plurality of kinds of optical disks whose usable wavelengths are different to one another, there is an apparatus which includes a plurality of objective lenses so as to obtain a focusing spot corresponding to each of the optical disks. (For example, refer to Patent Document 1.)    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-281758 (Pages 1 through 11, FIG. 2 through FIG. 13)

Optical driving device including a holder with a top face having a closed structure


Disclosed is an apparatus for recording information on and/or reproducing information from a disk-like recording medium with a light beam. The apparatus includes a box-like casing in which are provided a rotary drive mechanism for rotating the recording medium, an optical head having a movable portion on which at least an objective lens is mounted and a fixed portion on which at least the light source for emitting the light beam and a detector for detecting light reflected by the recording medium are mounted, and an electric circuit board having at least a control circuit for controlling the conditions of irradiation of the recording medium with the light beam and the movement of the optical head. Shielding plates are provided to separate the recording medium and the movable portion of the optical head from the rotary drive mechanism, the electric circuit board and the fixed portion of the optical head, and a cooling fan is also provided to cool the rotary drive mechanism, the electric circuit board and the fixed portion of the optical head.

1. Field of the Invention
This invention relates to an optical information recording/reproduction apparatus for optically recording and reproducing information by using a light beam.
2. Description of the Prior Art
An optical information recording/reproduction apparatus is capable of recording information based on a reduced size of a light spot formed on a recording medium by irradiating the recording medium with a light beam through an optical system and is therefore advantageous in increasing the recording density. A conventional apparatus of this kind constructed as an opto-magnetic information recording/reproduction apparatus will be described below.
As shown in FIGS. 1 and 2, a conventional optical information recording/reproduction apparatus has a cartridge insertion opening 3 which can be closed by a shutter and which is formed in a portion of a drive case 1. A disk cartridge 5 including a recording medium is inserted into or ejected out of the drive case 1 through the opening 3. A spindle motor 6 and a turntable 6a driven by the spindle motor 6 are provided in the drive case 1 to rotate the disk cartridge 5 at a constant speed. The disk cartridge 5 is fixed on the turntable 6a by a clamp means 6b such as a magnetic clamp. An optical head 8 for recording/reproducing information is disposed in the drive case 1. The optical head 8 is operated and controlled by a drive unit 12 moved in a radial direction of the recording medium. An optical system of such an apparatus includes a movable optical system provided on the optical head 8, and is constituted by an objective lens and a movable mirror (not shown). The optical system also includes a fixed optical system 9 which includes a laser provided as a light source and a detector (not shown) for detecting light reflected from the recording medium, and which is fixedly disposed on the apparatus opposite to the movable optical system. A magnetic field bias applying means 10 for applying a magnetic field bias to the recording medium is also provided in the drive case 1. The magnetic field bias applying means 10 applies a recording or erasing basing magnetic field to the recording medium at a position where the recording medium is irradiated with a light beam from the optical head 8. In the drive case 1 are further provided electric circuit boards including printed control circuit boards 11 on which are formed a circuit 7 for driving the spindle motor 6, a circuit (not shown) for controlling the magnetic field bias applying means 10 which opposes the optical head 8, a servo circuit (not shown) for controlling the state (e.g., tracking or focusing) of the light beam emitted from the optical head 8 and other circuits, and a circuit 15 for driving the optical head 8.
As shown in FIGS. 1 and 2, these components are housed as a unit in a container 2 placed in the drive case 1. The container 2 is supported on the drive case 1 by a vibration damping mechanism (not shown). A power source 13 for driving the above-noted components is separately provided in the drive case 1. A cooling fan 14 is provided on the drive case 1 to introduce air for cooling the power source 13 and then for directly cooling heating members as desired while causing air to flow to an air outlet 4 through ventilation openings 2a and 2b formed in walls of the container 2, as shown in FIG. 1, or the air directly cools the power source 13 after being introduced by the cooling fan 14, and indirectly cools the heating members in the container 2 by cooling outside walls of the container 2 while flowing through gaps between the container 2 and the drive case 1, as shown in FIG. 2. This cooling is intended to prevent damage to the information on the recording medium or deterioration of the performance of each of the semiconductor lasers serving as light sources and other electric parts due to an increase in the temperature in the drive case 1 or in the container 2 caused by the heat from the heating members in the container 2 of the apparatus.
In the former of these arrangements, as shown in FIG. 1, the heating members can be cooled by the cooling air introduced into the container 2, but there is a risk that any dust contained in the air will adhere to the optical system of the optical head and to the surface of the recording medium and, hence, will hinder correctly recording or reproducing information. In the case of the latter of these arrangements, as shown in FIG. 2, the heat sources, i.e., the spindle motor, the drive circuit, the light source of the fixed optical system, the printed control circuit board, and so on cannot be cooled sufficiently.
It is essential to efficiently cool the spindle motor, the drive circuit (for the light source and the spindle motor) and the printed control circuit boards, which are the primary heat sources.

Optical information recording/reproduction apparatus which cools components without adversely affecting operating efficiency


Pyrrolidine compounds described herein and methods for using them to inhibit dipeptidyl peptidase IV and treat Type II diabetes.

Dipeptidyl peptidase IV (DPP-IV), a member of the prolyl peptidase family, cleaves certain dipeptides at the penultimate position from the amino termini of the proteins. It contributes to rapid degradation of glucagon-like peptide-1 (GLP-1), a gut hormone produced by intestinal endocrine L-cells in response to food ingestion. GLP-1 in turn inhibits glucagon secretion and stimulates glucose-dependent insulin release from the pancreas (Zander M, et al. Lancet 2002, 359: 824-830). It has been shown that inhibiting DPP-IV resulted in enhanced insulin secretion, reduced plasma glucose levels, and improved pancreatic β-cell function (Pederson R. A., et al. Diabetes 1998, 47: 1253-1258; and Ahren B, et al. Diabetes Care 2002, 25: 869-875). DPP-IV inhibitors are therefore potential drug candidates for Type II diabetes.
Recent studies indicate that DPP-IV inhibitors were potential inhibitors of dipeptidyl peptidase VIII (DPP-VIII), another member of the prolyl peptidase family, and that inhibition of DPP-VIII resulted in side effects, e.g., toxicity and thrombocytopenia (Diabetes, 2005, 54: 2988-2994). Thus, DPP-IV inhibitors, as Type II diabetes drug candidates, preferably possess little or no inhibitory activity against DPP-VIII.

This patent is subject to a terminal disclaimer.


A switching circuit comprising a means for holding a signal or a DC component thereof, and a switching transistor for driving the holding means, wherein another means is included for shaping the trailing edge to be more obtuse in the fall of a driving pulse applied to a gate of the switching transistor. There is also disclosed a charge transfer device comprising a charge transferrer for transferring a signal charge, a charge-voltage converter for converting the transferred signal charge into a proportional voltage, and a driver for supplying a reset pulse to the charge-voltage converter so as to reset the capacitance thereof to a predetermined potential, wherein another a means is incorporated in the driver for shaping the trailing edge to be more obtuse in the fall of the reset pulse. Since the trailing edge of the reset pulse at the time of turning off the reset is rendered more obtuse, it becomes possible to reduce the coupling portion of the output waveform where the potential of a floating diffusion or a floating gate is varied by the capacitive coupling which is derived from the parasitic capacitance between a reset drain and a reset gate.

The present invention relates to a switching circuit and a charge transfer device using such a circuit in a portion of its output circuit.
FIG. 17 shows a structure of a solid-state image sensing apparatus such as a CCD linear sensor, and FIG. 18 shows a structure of the periphery of a charge voltage converter. First, a CCD linear sensor 170 comprises a sensor row 172 consisting of a multiplicity of sensor elements 171 (corresponding to, e.g., 2000 pixels) which are arrayed in a row to convert incident light into a signal charge of an amount proportional to the light quantity and store the signal charge therein, a read gate 173 for reading out the signal charge stored in each of the sensor elements 171 of the sensor row 172, and a charge transfer register 174 consisting of CCDs to unidirectionally transfer the signal charge read out by the read gate 173. The charge transfer register 174 is equipped with, at an end thereof, a charge-voltage converter 175 for detecting the transferred signal charge and converting such charge into a proportional voltage.
The read gate 173 is driven by a read gate pulse .o slashed.ROG applied thereto via a terminal 176. The charge transfer register 174 is driven by two-phase driving pulses .o slashed.1 and .o slashed.2 generated by a timing generator circuit 177 and applied via a driver 178. The charge-voltage converter 175 is reset by a reset pulse .o slashed.rs generated similarly by the timing generator circuit 177 and applied via the driver 178. The timing generator circuit 177 generates various timing signals, such as two-phase driving pulses .o slashed.1, .o slashed.2 and a reset pulse .o slashed.rs, in response to clock pulses .o slashed.CLK inputted thereto via a terminal 179. An output voltage V.sub.fd from the charge-voltage converter 175 is first supplied to a buffer 181 and then is delivered therefrom as a CCD output voltage V.sub.out via an output terminal 181. Subsequently the voltage V.sub.out is converted into a digital signal by an AD converter 182 in accordance with an AD timing pulse.
In FIG. 18, the charge-voltage converter 175 is constructed as a floating diffusion amplifier which consists of a floating diffusion (FD) 184 composed of N+ type impurity and formed adjacently to the output gate 183 which is composed of N- type impurity and constitutes the final stage of the charge transfer register 174, a reset drain (RD) 185 composed of N+ type impurity and formed via a channel region of N type impurity, and a reset gate (RG) 186 disposed above the channel region, wherein the signal charge transferred from the output gate 183 to the floating diffusion 184 is converted into a voltage V.sub.fd and then is outputted. A predetermined voltage (e.g., supply voltage V.sub.dd) is applied as a reset drain voltage V.sub.rd to the reset drain 185. Meanwhile the aforementioned reset pulse .o slashed.rs is applied to the reset gate 186.
FIG. 19 shows a general output waveform of the CCD output voltage V.sub.out obtained when none of sample and hold action (S/H) is performed in the buffer 180. As obvious from this output waveform, when a reset pulse .o slashed.rs applied to the reset gate 186 is turned off, there occurs a .o slashed.rs coupling which signifies a potential variation caused in the floating diffusion 184 due to capacitive coupling derived from a parasitic capacitance between the reset drain 185 and the reset gate 186. Supposing now that the CCD output voltage V.sub.out has an amplitude of 1V.sub.p--p, if the .o slashed.rs coupling is 0.5V, it follows that a voltage of 1.5V or more needs to be ensured for the operating region of the output circuit in consideration of some amplitude variation of the .o slashed.rs coupling (derived from variations in manufacture and ambient environment in use). In view of the above situation, it is essential to reduce the .o slashed.rs coupling for facilitating design of the output circuit.
FIG. 20 shows an output waveform of the CCD output voltage V.sub.out obtained when a sample holding action is performed in the buffer 180. Although the entire amplitude of the CCD output voltage V.sub.out is also reduced by such a sample holding action, it becomes necessary to take the .o slashed.rs coupling into consideration in designing a front stage 187 of the sample hold circuit 186 (consisting of two source-follower stages in this example), as obvious from the circuit diagram of FIG. 18. Further when CDS (correlated double sampling) or the like is to be executed for elimination of noise, the circuit configuration anterior to the sample hold circuit 186 is complicated since such CDS needs to be performed prior to the sample holding action. And the more complicate the circuit configuration is rendered, there exist greater difficulties in designing a large operating region.
Another problem existing with regard to the .o slashed.rs coupling relates to noise. One of noises included in the CCD output voltage V.sub.out is random noise which is termed reset noise in a broad sense. The reset noise is classified into resistance noise in its narrow sense, distribution noise caused when the charge under the gate is distributed to the floating diffusion at turn-off of the reset gate 186, and coupling noise caused by variation of the .o slashed.rs coupling derived from capacitive coupling. Here, distribution noise and coupling noise are dependent on the reset pulse .o slashed.rs.
The distribution noise raises a problem relative to distribution of the charge on a channel or to a transfer time to the drain at (or immediately after) turn-off of a transistor (MOS transistor consisting of floating diffusion 184, reset drain 185 and reset gate 186) in the reset gate. If the mutual conductance g.sub.m of the MOS transistor is sufficiently high, the distribution noise changes depending on its turn-off speed. And this noise becomes larger in accordance with increase of the speed. The speed is determined on the basis of the value obtained by dividing the amplitude of the .o slashed.rs coupling by the fall time of the reset pulse .o slashed.rs.
As for the coupling noise, some influence is derived from the impedance due to wiring and so forth to the reset drain 185 supplied normally with the source voltage V.sub.dd and also from the MOS transistor in the reset gate, and the coupling noise is dependent on the fall speed of the rest pulse .o slashed.rs. More specifically, when the impedance is high, the coupling is increased by the parasitic capacitance between the reset drain 185 and the reset gate 186, whereby the noise is also increased. To the contrary, when the fall speed of the reset pulse .o slashed.rs is low, the coupling is reduced by the influence from the impedance and the MOS transistor in the reset gate. To realize reduction of the coupling itself is significant in view of both design and performance, as described.
For reduction of the coupling, there are the following means. First, FIG. 21 is a circuit diagram of a fundamental .o slashed.rs driver. This .o slashed.rs driver comprises a first-stage C-MOS inverter 211 consisting of a P-MOS transistor M1 and an N-MOS transistor M2 connected between a power supply V.sub.dd and the ground, a second-stage C-MOS inverter 212 consisting of a P-MOS transistor M3 and an N-MOS transistor M4 connected between the power supply V.sub.dd and the ground similarly to the above, and a load capacitor CL connected between an output line 213 and the ground. In contrast with the .o slashed.rs driver having such a circuit configuration, the present example is so contrived as shown in FIG. 22 for realizing reduction of the coupling, wherein the source of an N-MOS transistor M4 in a second-stage C-MOS inverter 212 is connected to a power supply V.sub.cc. The output voltage of this power supply V.sub.cc is intermediate between the voltage of the power supply V.sub.dd and the ground level.
FIGS. 23A and 23B show waveforms of reset pulses .o slashed.rs and CCD outputs V.sub.out, respectively, in the circuit examples 1 and 2 of FIGS. 21 and 22. And FIG. 24 shows cross-section potentials in the vicinity of a floating diffusion (FD) at time points t1, t2 and t3 in FIGS. 23A and 23B. According to the circuit example 2 of FIG. 22, the low level of the reset pulse .o slashed.rs is set to be higher than that in the circuit example 1 of FIG. 21 as denoted by a single-dot chained line in FIG. 23A, so that the amplitude of the reset pulse .o slashed.rs itself can be diminished, whereby the coupling to the output V.sub.fd of the floating diffusion is also reducible correspondingly thereto, as obvious from FIG. 23B. However, if the amplitude of the reset pulse .o slashed.rs is diminished extremely, it becomes impossible to sufficiently ensure the dynamic range of the floating diffusion. Therefore, in the related art mentioned above, there exists some restriction in diminishing the amplitude of the reset pulse .o slashed.rs to a certain degree to consequently limit the reduction of the coupling as well.

Switching circuit and charge transfer device using same


In order to create a method for making available driving lane recommendations for each driving direction relating to at least one curb and interlinked with one another, as well as a system related thereto, which improve the quality of the driving instructions provided by a navigation device via optimized processing of the driving lanes on roads, in particular at intersections, it is recommended that (a) a curb (10, 11, 12; 10′, 12′, 15′) be assigned at least one lane list (20) whose elements (20.a.1.1, 20.a.1.2, 20.a.2) contain lane information on the totality of the driving lanes assigned to the curb (10, 11, 12; 10′, 12′, 15′); (b) each of the driving lanes be assigned at least one lane data list (30; 40) whose elements (30.b.1, 30.b.2; 40.b.1, 40.b.2) each contain lane data information on the particular driving lane; and (c) each follow-on driving lane succeeding the driving lane be assigned at least one follow-on lane list (50; 60; 70) whose elements (50.c.1, 50.c.2, 50.c.3, 50.c.4; 60.c.1, 60.c.2, 60. c.3, 60.c.4; 70.c.1, 70.c.2, 70.c.3, 70.c.4) each contain follow-on lane information, interlinked with the lane data information of the preceding driving lane, on the particular follow-on driving lane.

In means of transportation such as motor vehicles, permanently installed navigation devices simply, quickly, and safely guide the driver of a means of transportation from the current location to a desired destination without the driver of the means of transportation first having to elaborately plan a route and obtain appropriate maps.
For this purpose, appropriate navigation data based on charts, maps, or street maps are available stored, for example, on CD-ROM (=Compact Disc-Read Only Memory) or on DVD (=Digital Versatile Disc). The navigation device uses GPS (=Global Positioning System), for example, in order to determine the current location and calculate the appropriate navigation instructions that lead to the predetermined destination. The navigation data, in this connection, preferably contains data on roads and paths for motor vehicles.
An important component of the above-mentioned basic function of a navigation device is the processing of the driving lanes on the roads, especially before, at, and after intersections. Driving lanes, in this case, are to be understood as the fanning out of the driving directions, in particular before an intersection, painted on the road.
The processing of such driving lanes, which may be found directly on the road surface or on signs installed above the roads such as in the form of sign bridges and/or electronic alternative-route indicators having directional symbols and/or distant destinations, will initially be required only at freeway interchanges, but later also at all other intersections having driving lanes.
In this context, it must be considered, however, that so far, in conventional navigation devices, the processing of linked consecutive driving lanes is still inadequate. The driver of the means of transportation is not provided with information by the navigation device enabling him to optimally navigate the means of transportation through street traffic, especially in the case of a rapid succession of multiple intersections or forks in the road.

Method and system for making available driving lane recommendations


The present invention provides compositions and methods for enhancing oil recovery from low permeability subterranean formation using three mechanisms: repressurization; reduction of interfacial tension; and increased permeability. The subject compositions comprise a chelating agent, a biosurfactant, a carbonate or bicarbonate salt, water, and a pH adjusting substance, which when applied to an oil-bearing formation according to the methods of the subject invention, allow for controlled release of carbon dioxide within the formation without complicated machinery or gas-producing microorganisms.

Oil exists in small pores and narrow fissures within the body of reservoir rocks underneath the surface of the earth. Natural pressure of the reservoir causes the oil to flow up to the surface, thereby providing primary production of an oil well. As oil production progresses, however, the reservoir pressure is depleted to a point at which artificial lift or pumping is required to maintain an economical oil production rate. In these situations, the formation may still contain significant amounts of oil, but the decreased formation pressure reduces the flow capacity of the oil out of the wellbore.
When it is necessary to provide external energy for the reservoir to achieve additional oil recovery (secondary oil recovery), there exist technologies for increasing pressure in a reservoir to "push" the remaining oil to the surface. One method involves injecting gas, e.g., carbon dioxide or nitrogen into an oil reservoir, while another method involves injecting water (waterflooding). The effect is a repressurization of the reservoir, causing oil displacement from trapped capillaries and enhancing mobilization of the oil to the producing wells. While these methods can be useful for producing a certain amount of additional oil, the methods often must overcome the challenges of, for example, low or variable permeability within a formation.
With waterflooding, for example, injected fluids flow preferentially along highly permeable layers, by-passing oil-saturated areas, or oil "islands," in the reservoir. Therefore, an increasing quantity of water rises with the oil and, by decreasing the ratio of oil to water, it eventually becomes uneconomical to continue the process.
Additionally, some hydrocarbon-bearing formations have normal to high porosity, but have low permeability. This means that the formation may contain significant amounts of oil but have small flow channels or limited fractures through which gases and liquids, including oil, could flow. For example, the diatomite reserves in California, Lost Hills and Belridge, contain approximately 10 billion barrels of oil. When intact, the diatomite has porosity of 50-70% and is almost impermeable (0.1-1.0 millidarcy (md)). Oil recovery from this type of formation is usually quite limited using conventional primary and secondary recovery techniques, such as waterflooding, and often must employ hydrofracturing techniques to alter the structure of the rocks.
Low permeability can also be a result of organic and/or inorganic deposits in the formation, such as mineral scales. Scale deposits can occur during water flooding operations, when mineral salts precipitate as a result of injected water or brine coming into contact with other formation fluids or the formation itself, as well as changes in the pressure, composition and/or temperature of the formation or crude oil. Scales can comprise precipitates of, for example, barium sulfate, barium carbonate, calcium carbonate, strontium carbonate, strontium sulfate, calcium sulfate, sodium chloride, silicon dioxide, iron sulfide, iron oxides, iron carbonate, silicates, phosphates and oxides, or any of a number of compounds that are insoluble or mildly soluble in water.
Systematic treatment or removal of deposits is crucial to formation maintenance. As reservoir pressure drops, oil production and flow rates decrease. The slowing of flow rates leads to the buildup of films and chemicals in the pores of the formation, thus reducing permeability and hydrocarbon movement into the wellbore. This can lead to changes in temperature gradients and thus even greater precipitation of deposits, including scale. Thus, the effects are interrelated, cyclical and compounding.
Additional challenges can arise with certain gas injection techniques, which are often technologically difficult to implement. For example, obtaining high volumes of immiscible gas can be costly and might even require constructing a plant for producing the gas at the site of the oilfield. Furthermore, there are costs and safety concerns related to gas compression and pumping, which can require complicated machinery, and the success of oil recovery can be unpredictable in the end due to, for example, variable reservoir characteristics.
One solution to these challenges could be the use of gas-producing microorganisms in Microbial Enhanced Oil Recovery (MEOR). MEOR involves the use of specific bacteria capable of producing useful metabolites in situ, such as gases, acids, surfactants, solvents and polymers, that help with post-primary recovery of residual oil. The production of biogenic gases in situ, which can include carbon dioxide, hydrogen, methane and nitrogen, can help with repressurizing a reservoir, as well as with reduction of the oil viscosity by solution of the gas in the oil. Examples of gas-producing bacteria are Clostridium, Desulfovibrio, Pseudomonas, and some methanogens.
While in situ gas production can be useful in that pumping of gas from the surface is not required, the longer a microbiome is permitted to develop within a formation, the greater the risk is for the establishment of microorganisms that produce deleterious metabolites. For example, certain bacteria that grow within a formation produce hydrogen sulfide, carbonic acid and other corrosive metabolites.
The "recoverable reserves" of a particular well are an important measure of how profitable the well will likely be. Reserves are considered recoverable if they are economically and technologically feasible to extract at the existing price of oil and gas. In other words, recoverable reserves are those that can be developed with reasonable certainty under current economic conditions, operating methods and government regulations.
Many wells contain a large volume of reserves that, because of the nature of the formation, remain unrecoverable. The permeability of a subterranean formation, in particular, can have a profound effect on the ability of conventional oil recovery methods to produce the full potential volume of oil from a formation. Low and/or variable permeability formations, for example, often contain saturated oil "islands," which are by-passed by fluids and gases that favor higher permeability channels within the formation.
Because of the billions of gallons of oil that remain unrecovered from these reserves, there is a need in the art for safe, effective, environmentally-friendly, and economical means for increasing recoverable reserves, particularly from formations having low or variable permeability. In particular, there is a need for improved methods of repressurizing subterranean formations.

Compositions and methods for enhanced oil recovery from low permeability formations


A single use, transportable reaction crucible for a metallothermic welding portion is provided. A separate cylindrical reaction vessel is disposed in the cylindrical casing of a non-metallic crucible shell, which has a flat base and a lid. The reaction vessel is supported on the base of the crucible shell and accommodates a welding portion. The outer diameter of the reaction vessel is less than an inner diameter of the cylindrical casing, with refractory material filling the annular intermediate space thereby formed between the reaction vessel and the cylindrical casing.

The present invention relates to a single use transportable reaction crucible for a metallothermic, especially aluminothermic, welding portion and includes a crucible shell having a cylindrical casing and a flat floor and a lid and in the crucible shell a refractory lining that receives the welding portion and that is provided in its base with an opening that can melt open.
Such a reaction crucible is known from DE 197 02 410 C1. In the known reaction crucible, the actual reaction crucible is stamped or riveted into a metal crucible shell in the form of a lining made of a sand mixture. For this reason the shell must be made from a high-strength, metallic, heavy material. A lighter and less expensive material such as cardboard, plastic, or the like cannot be used. Since the lining has a flat floor corresponding to the flat floor of the crucible shell, it does not facilitate the flow of the molten metal to the bottom opening. In the lining the welding portion is either fed into a conventional can or into a conventional plastic sack or into another container. When the reaction crucible is used, the lid is removed and the welding portion is ignited using an ignition rod, whereupon the lid is replaced. The metal crucible shell requires a separate removal from the application site.
The object of the present invention is to provide a reaction crucible of the aforementioned type in which less expensive materials can be used for the crucible shell and the actual reaction crucible is securely maintained in the crucible shell and has an inclined floor.
This object is achieved in that placed on the flat floor of the crucible shell, which is made of a non-metal material, is the flat underside of a support disc made of a refractory material and adapted to the interior diameter of the casing, the top surface of which forms a cone in the direction of a central opening, and in that the refractory lining is a specially produced cylindrical reaction vessel that has been inserted into the casing, the floor of which is configured in the shape of a cone to correspond to the top surface of the support disc and is placed on the disc and engages the central opening of the support disc with a hollow guide projection.
Since the crucible shell does not simultaneously have to serve as the exterior profile for the reaction vessel, it can be produced from a non-metallic material such as cardboard, laminated paper, plastic, or the like. At least the cylindrical casing and the floor of the crucible shell comprise preferably cardboard, plastic, or the like. Cardboard is particularly preferred for the material. The reaction vessel, which is produced as a separate component, is provided with a conical floor. The support disc ensures that the reaction vessel is securely supported and centered in the crucible shell.
Production tolerances during the manufacture of the reaction vessel and/or the construction of the overall wall thickness required for the melting reaction can be compensated in a preferred manner in that the outer diameter of the reaction vessel is smaller by a pre-specified amount than the inner diameter of the casing and the annular intermediate space is filled with a refractory material, preferably in the form of small particles.
There are a plurality of options for the design of the crucible shell. For instance, it is possible that the cylindrical casing and the floor of the crucible shell and at least one lid of the reaction crucible, the lid preferably being provided with an opening, are made of cardboard, laminated paper, or the like. The lid of the reaction crucible is thus made from the same material as the crucible shell. On the other hand, it is also possible that at least one lid of the reaction crucible, the lid preferably being provided with an opening, comprises a refractory material. In addition, it can be useful to use a double-lidded system in which an exterior lid made from one of the other materials cited in the foregoing is placed on an interior lid made of a refractory material.
In order to maintain the lid securely in place, it is advantageous when the cylindrical casing of the crucible shell extends beyond the free edge of the reaction vessel and at least one of the lids rests upon the free edge of the reaction vessel and is maintained by the overhanging section of the casing.
In order to ensure that the closure remains air-tight and/or moisture-tight, it is useful that, in addition to the lid or lids, a film is provided on the exterior side thereof as a protective and/or sealing protecting element, said film preferably covering the upper edge of the crucible shell casing.
It is thereby also possible that the parts of the crucible shell that are made of cardboard, plastic, or the like are protected from the penetration of moisture in that, e.g. if cardboard is used for the crucible cover, the cardboard is lined on its interior side with a metal film or the cardboard is provided with a film on the interior.
The guide projection can be embodied integrally with the reaction vessel or as a separate component. Embodying it separately facilitates inserting the melting seal into the guide projection that defines the floor opening of the reaction vessel.
At many sites where the metallothermic welding process is used, e.g. tunnels, it is desirable that dust be removed from gases exiting the reaction crucible. Therefore, it is useful when the opening in the lid is provided with a filter made of a refractory nonwoven web. It can be useful when an additional ignition opening is provided in the lid when the filter is joined securely to the lid over the exhaust opening.
A particularly stable construction of the crucible shell results when the floor of the crucible shell is provided with a circular flange and is glued into the casing such that the free edges of the casing and flange lie in the same plane.
Preferably a different refractory material is used for the support disc than is used for the reaction vessel, since the support disc undergoes less thermal stress when the crucible is used than does the reaction vessel. The filler material for the annular gap between casing and reaction vessel also undergoes less thermal stress than the reaction vessel and can therefore also be different.
In the reaction crucible in accordance with the invention, the welding portion is preferably introduced into the reaction vessel as free fill and the lid or lids are sealed air-tight and/or moisture-tight.

Single use transportable reaction crucible for a metallothermic welding portion


When a buffer is formed by using transistors having large element characteristic variations, the deviation of the timing between the input clock pulse and the reset pulse is likely to occur. When the deviation of the timing becomes larger, a malfunction is caused to occur, and an operation margin becomes smaller with respect to the variations of the element characteristics. In a timing generation circuit, which is formed on an insulating substrate and which has two TFFs (12, 13), for generating a dot clock DCK and a horizontal clock HCK whose frequencies are different in synchronization with a master clock MCK which is input external to the substrate, separate reset pulses drst and hrst are generated at a pulse generation circuit 15 with respect to the two TFFs (12, 13), and a resetting operation is performed at separate timings. Thus, a large operation margin can be ensured even when each circuit is formed by using TFTs having large element characteristic variations and a rough process rule.

A conventional example of a timing generation circuit, which is one type of logic circuit, is shown in FIG. 7. The timing generation circuit according to this conventional example is configured to have a level-shift circuit 101, and two flip-flops which are cascade-connected in sequence to the output thereof, that is, T-type flip-flops (hereinafter referred to as "TFFs") 102 and 103 in this example. The level-shift circuit 101 level-shifts (level-converts) a master clock MCK of a low voltage amplitude, which is input externally, into a master clock lsmck of a high voltage amplitude. This master clock lsmck is supplied via a buffer 104 to a circuit which operates by using the master clock lsmck as a reference.
The TFF 102 generates a dot clock DCK by frequency-dividing the master clock lsmck. This dot clock DCK is supplied via a buffer 105 to a circuit which operates by using the dot clock DCK as a reference. The TFF 103 generates a horizontal clock HCK by further frequency-dividing the dot clock DCK. This horizontal clock HCK is supplied to a circuit which operates by using the horizontal clock HCK as a reference.
The TFFs 102 and 103 are reset in accordance with a reset pulse which is given externally, for example, at a 1H (H is a horizontal period) period. Here, wiring for transmitting the reset pulse to the TFFs 102 and 103 has a wiring capacity, a transistor input capacity, and a cross capacity with the other wiring. For this reason, a configuration is adopted in which the driving capability for a load capacity is increased by using a buffer 106 having a capability enough to drive such load capacities.
In the timing generation circuit having the above-mentioned configuration, in a case where each circuit part is formed by using transistors having large characteristic variations, the deviation of timings between each input clock pulse of the TFFs 102 and 103 and the reset pulse is likely to occur. When the deviation of timings becomes larger, problems arise in that a malfunction occurs, and the operation margin becomes smaller with respect to element characteristic variations.
Here, the circuit operation of the timing generation circuit having the above-mentioned configuration will be described with reference to the timing charts in FIGS. 8A and 8B.
During the normal operation, as shown in FIG. 8A, the TFFs 102 and 103 repeat the operation of their state being inverted in synchronization with the rise of the input clock pulse, thereby generating an output pulse whose period is twice as long as that of the input clock pulse. Furthermore, when a low-level reset pulse is given, the output pulse becomes a low level as a result of being reset at the timing of the fall thereof, and the output pulse shifts to a high level at the rise timing of the first input clock pulse after the reset pulse shifts to a high level. Thereafter, the TFFs 102 and 103 continue to generate the output pulse in synchronization with the input clock pulse over the period in which the next reset pulse is given.
On the other hand, during malfunction such as the relative timing relationship between the input clock pulse and the reset pulse being deviated due to element characteristic variations, for example, as shown in FIG. 8B, when the reset pulse which occurs in a period in which the input clock pulse is at a low level during the normal operation tap (FIG. 8A) occurs in a period in which the input clock pulse is at a high level, the reset operation is continued also after the rise timing of the next input clock pulse. Consequently, a malfunction of the polarity of the output pulse after the reset occurs.
The deviation of the relative timing relationship between the input clock pulse and the reset pulse occurs from the difference in the amount of delay between the circuits which generate these pulses, that is, the level-shift circuit 101 and the TFFs 102 and 103, and the buffer 107. In a case where these circuits are formed by using Thin-Film Transistors (TFTs) having large element characteristic variations and having a rough process rule (for example, 3.5 μm), the amount of delay is large, and, in particular, the difference is likely to occur.
The present invention has been made in view of the above-described problems. An object of the present invention is to provide a logic circuit capable of ensuring a large operation margin even when it is formed by using transistors having variations in characteristics and having a rough process rule, a timing generation circuit using the logic circuit, a display device using the timing generation circuit as one of peripheral driving circuits, and a portable terminal having incorporated therein the display device as a display output section.

Logic circuit, timing generation circuit, display device, and portable terminal


The present invention relates to specific photochromic phenanthropyrans as well as to their use in synthetic resin materials of all types, especially for ophthalmic purposes. In particular, the present invention relates to photochromic compounds derived from 2H-phenanthro[2,1-b]pyrans and 3H-phenanthro[3,4-b]pyrans, which in the open form have especially long wavelength absorption maxima, but in the unexcited state are still colorless.

The present invention relates to specific photochromic phenanthropyrans, as well as to their use in synthetic resin materials of all types, especially for ophthalmic purposes. In particular, the present invention relates to photochromic compounds, which are derived from 2H-phenanthro[2,1-b]pyrans and 3H-phenanthro[3,4-b]pyrans, which, in the open form, have particularly long-wave absorption maxima, but are still colorless in the unexcited state.
Different classes of dyes are known, which, when irradiated with light of particular wavelengths, especially sunlight, change their color reversibly. This comes about because of the fact that, due to the supply of energy in the form of light, these dye molecules transition into an excited, colored state, which they leave once again when the supply of energy is interrupted, as a result of which they return to their colorless or hardly colored normal state. These photochromic dyes include, for example, the naphthopyrans, which have already been described in the state of the art with different substituents.
Pyrans, especially naphthopyrans and larger ring systems derived from naphthopyrans, are photochromic compounds, which have been the subject of intensive investigations up to the present time. Although the first patents were applied for as early as 1966 (U.S. Pat. No. 3,567,605), compounds, which appeared to be suitable for use in lenses for eyeglasses, were developed only in the 1990s.
The dyes, known from the prior art, frequently have inadequate long-wave absorption in the excited as well as in the unexcited state. This leads to problems even when such dyes are combined with other photochromic dyes. Furthermore, such dyes frequently also exhibit an excessively high temperature sensitivity with respect to the darkening and, at the same time, the lightening or fade is too slow. Moreover, the durability of the dyes available in the prior art frequently is insufficient. Consequently, the durability of such lenses for sunglasses is inadequate. This becomes noticeable due the rapidly decreasing performance and/or the strong yellowing which occurs.
3H-Naphthopyrans, derived from 2-naphthols, and their higher analog derivatives derived by annellation constitute a group of photochromic dyes, the longest wavelength absorption maximum of the excited form of which lies predominantly in the spectral range from 420 nm to 500 nm and accordingly cause a yellow, orange or red-orange color sensation (see U.S. Pat. Nos. 5,869,658 and 6,022,495). However, high-performance, violet to blue photochromic dyes are required for neutral, darkening phototropic glasses. Violet to blue photochromic dyes which are currently available in the art, usually originate from the class of spiroxazine dyes, fulgide dyes or 2H-naphtho[1,2-b]pyrans. Usually, however, spiroxazine dyes are disadvantageous with respect to their high-temperature performance, and fulgide dyes and 2H-naphtho[1,2-b]pyrans have properties which are not completely satisfactory for use in lenses for sunglasses, the former because of the durability and the latter because of the lightening rate.
The introduction of electron-displacing substituents on the aryl groups in the ortho position to the pyran oxygen, as described, for example, in WO 98/45281, WO 01/12619 and EP 0 945 451 A1 leads to red or red violet darkening 3H-naphtho[2,1-b]pyrans. WO 01/12619 discloses compounds in which one geminal aryl group has a para-amino-substituted group and the other aryl group has an alkoxy group or a thioalkoxy group, substituted in the meta or para position, this substitution pattern having a positive effect on the lightening rate. WO 98/45281 describes red hyperchromic compounds which additionally contain an amine function predominantly in the 6-position of the 3H-naphtho[2,1-b]pyran unit. Compounds, with amino groups which do not have pronounced basic properties are described in EP 0 945 451 A1. In the excited state, these compounds show a pink to violet color and have an attractive durability. 3H-Naphtho[2,1-b]pyrans with an aryl substituent in the 6-position are furthermore described in WO 99/31082. The effect of the aryl substitution in the 6-position on the longest wavelength absorption maximum of the unexcited as well as the excited form is, however, very slight in these compounds.
Appropriate substitution in the 8-position of the 3H-naphtho[2,1-b]pyran unit brings about a bathochromic shift in the longest wavelength absorption maximum, especially due to the introduction of alkoxy groups, as described in U.S. Pat. No. 5,238,981. In addition, compounds with dialkylamino groups in the 8-position are also disclosed. The use of nitrogen heterocyclic groups as substituents in the 8-position of the 3H-naphtho[2,1-b]pyran unit is mentioned in U.S. Pat. No. 5,990,305, as a result of which, in contrast to open-chain amino groups, an improved durability is obtained. This is also achieved with substituents which contain so-called HALS (hindered amine light stabilizer) structural units. Finally, violet to blue 3H-naphthol[2,1-b]pyrans, which have substituents containing amino groups in the 3-position as well as in the 8-position, are described in WO 03/055872, and blue 3H-naphthol[2,1-b]pyrans which contain a substituent in the 6-position in addition to the above substituents in the 3 and 8-positions are described in WO 03/080595.
Larger aromatic ring systems, which contain a naphthopyran unit, are described, for example, in U.S. Pat. Nos. 5,106,998, 5,888,432, 4,826,977 and 5,637,709. However, the compounds are not substituted with two aryl groups in the 3-position and instead have at least one saturated polycyclic substituent and thus lead to yellow to red photochromic compounds in the excited form.
Furthermore, U.S. Pat. Nos. 5,565,147, 5,674,432 and 6,294,112 (WO 98/45281) disclose photochromic 3H-naphtho[2,1-b]pyrans which have an annellated heterocyclic unit at the different sides of the naphthalene unit. Accordingly, red hyperchromic 3H-naphtho[2,1-b]pyrans, which may be annellated heterocyclically, are described in U.S. Pat. No. 6,294,112 (WO 98/45281). EP 1 038 870 A1 describes 3H-naphtho[2,1-b]pyrans which have an optionally substituted amido group in the 5-position and the naphthopyran unit of which may be expanded by a heterocyclic or aromatic ring.
Substituted phenanthropyrans are described in U.S. Pat. Nos. 5,514,817 and 6,210,608. These are derived, however, from 2H-naphtho[1,2-b]pyrans.