Constraint-based methods for determining orientations of material physical properties using an isoparametric shape function are disclosed. In one embodiment, a method of defining an orientation of an material physical property includes defining nonlinear and/or discontinuous design constraints of design values in a geometric domain associated with one or more physical attributes of the material physical property, and translating the nonlinear and/or discontinuous design constraints into continuous, first order design constraints of the design values by applying an isoparametric shape function. The method further includes performing a topology optimization using the continuous, first order design constraints of the design values, and reverse-translating results of the topology optimization back into the geometric domain using the isoparametric shape function. The results of the topology optimization in the geometric domain are indicative of the orientation of the material physical property.

Computer aided engineering analysis, for example, topology optimization techniques such as finite element models (FEM), incorporate computational techniques that are used to find approximate solutions to engineering problems. In general, a model representing the geometry of interest is discretized into a plurality of elements that collectively represent the entire geometry. Because of the elements' reduced size, computers executing the FEM analysis are capable of solving the partial differential equations that govern the physical properties of each of the elements and, therefore, provide an approximate solution to the physical problem for the entire geometry of interest.
Defining in the FEM model the orientation of the material physical property or properties (e.g., magnetic north of a permanent magnet) in polar coordinates (i.e., radius and angle of orientation) imposes a non-continuous design constraint on the material physical property because the angle of orientation is between 0° and 360°. Similarly, limiting the orientation of the material physical property using a Cartesian coordinate system imposes a nonlinear design constraint on the property because the position of the property must satisfy a second-order condition (i.e., (x2+y2)1/2<1).
Another difficulty in optimizing the orientation of material physical properties includes application of design constraints that are non-continuous. For example, properties may be limited in orientation to a pre-determined number of directions in the physical domain. For example, manufacturing constraints may limit the orientation of the property, such as the direction of magnetic fields of magnets in a magnetic system, into four, six, or eight directions.
Using traditional optimization techniques, the material properties of each of the finite elements would have non-continuous design constraints applied, which increases optimization model complexity and computational time to complete convergence of the optimization model. Further, incorporating such a model with non-continuous design constraints into an optimization routine may be difficult or prohibitive, as the optimization model having non-continuous design constraints may lack the flexibility to make incremental changes to the orientation of the material physical properties of the elements while allowing the optimization model to converge.
Accordingly, a need exists for alternative methods for convergence of nonlinear programming problems that involve angles as material property design variables, and promoting convergence of the material property design variable angles into a set of specified desired angles.

Methods for orienting material physical properties using constraint transformation and isoparametric shape functions

Toyota Motor Engineering & Manufacturing North America, Inc.


An R-410A DX heating/cooling system with: an electrical generating expansion device; with a protective means for refrigerant transport tubing containing dissimilar metals and/or in corrosive environments; with an automatic heating mode expansion device; with a TXV by-pass design; with retractable sub-surface tubing designs; with sub-surface line set sizing at varying depths and lengths; with reciprocal compressor sizing; with a DX Hydronic system design; with an improved oil separator float design; with a mobile DX system design; and with a resting module DX system design.

Geothermal ground source/water source heat exchange systems typically use fluid-filled closed loops of tubing buried in the ground, or submerged in a body of water, so as to either absorb heat from, or to reject heat into, the naturally occurring geothermal mass and/or water surrounding the buried or submerged fluid transport tubing. The tubing loop is extended to the surface and is then used to circulate one of the naturally warmed and naturally cooled fluid to an interior air heat exchange means.
Common and older design geothermal water-source heating/cooling systems typically circulate, via a water pump, a fluid comprised of water, or water with anti-freeze, in plastic (typically polyethylene) underground geothermal tubing so as to transfer geothermal heat to or from the ground in a first heat exchange step. Via a second heat exchange step, a refrigerant heat pump system is used to transfer heat to or from the water. Finally, via a third heat exchange step, an interior air handler (typically comprised of finned tubing and a fan, as is well understood by those skilled in the art) is used to transfer heat to or from the refrigerant to heat or cool interior air space.
Newer design geothermal DX heat exchange systems, where the refrigerant fluid transport lines are placed directly in the sub-surface ground and/or water, typically circulate a refrigerant fluid, such as R-22 or the like, in sub-surface refrigerant lines, typically comprised of copper tubing, to transfer geothermal heat to or from the sub-surface elements via a first heat exchange step. DX systems only require a second heat exchange step to transfer heat to or from the interior air space, typically also by means of an interior air handler. Consequently, DX systems are generally more efficient than water-source systems because less heat exchange steps are required and because no water pump energy expenditure is necessary. Further, since copper is a better heat conductor than most plastics, and since the refrigerant fluid circulating within the copper tubing of a DX system generally has a greater temperature differential with the surrounding ground than the water circulating within the plastic tubing of a water-source system, generally, less excavation and drilling is required, and installation costs are lower, with a DX system than with a water-source system.
While most in-ground/in-water DX heat exchange designs are feasible, various improvements have been developed intended to enhance overall system operational efficiencies. Several such design improvements, particularly in direct expansion/direct exchange geothermal heat pump systems, are taught in U.S. Pat. No. 5,623,986 to Wiggs; in U.S. Pat. No. 5,816,314 to Wiggs, et al.; in U.S. Pat. No. 5,946,928 to Wiggs; and in U.S. Pat. No. 6,615,601 B1 to Wiggs, the disclosures of which are incorporated herein by reference. Such disclosures encompass both horizontally and vertically oriented sub-surface heat geothermal heat exchange means, using historically conventional refrigerants, such as R-22 . The use of a refrigerant operating at higher pressures than R-22, such as R-410A, has been found to be advantageous for use in a DX system incorporating at least one of the disclosures as taught herein. R-410A is an HFC azeotropic mixture of HFC-32 and HFC-125.
DX heating/cooling systems have multiple primary objectives. The first is to provide the greatest possible operational efficiencies. This directly translates into providing the lowest possible heating/cooling operational costs, as well as other advantages, such as, for example, materially assisting in reducing peaking concerns for utility companies. A second is to operate in an environmentally safe manner by using environmentally safe components and fluids. A third is to provide an economically feasible installation means at the lowest possible initial cost, so as to enhance system payback opportunities. A fourth is to provide sub-surface installation means within the smallest surface area possible. A fifth is to increase interior comfort levels. A sixth is to increase long-term system durability, and a seventh is to facilitate ease of service and maintenance.
Historically, DX heating/cooling systems, even though more efficient than other conventional heating/cooling systems, have experienced practical limitations created by the relatively large surface land areas necessary to accommodate the sub-surface heat exchange tubing. For example, with R-22 systems, a typical land area of 500 square feet per ton of system design capacity was required in first generation designs to accommodate a shallow (within 10 feet of the surface) matrix of multiple, distributed, copper heat exchange tubes. Early generation borehole designs still required about one 50 foot, to one 100 foot, (maximum) depth wells/boreholes per ton of system design capacity, preferably spaced at least about 20 feet apart. Such requisite surface areas effectively precluded system applications in many commercial and/or high density residential applications.
The subject disclosures primarily relate to DX systems installed with vertically oriented sub-surface geothermal heat exchange means, although a means to use the subject disclosure in a lake, in a fully water saturated borehole, or the like, is also disclosed. In a DX system design, primary objectives are to increase system operational efficiency levels, to reduce installation costs, to increase interior comfort levels, to increase long-term system durability, and to facilitate ease of service and maintenance. Also, a means of installing a DX Hydronic system is disclosed, with an objective of applying DX system advantages, in lieu of conventional boiler/chiller systems, and in lieu of traditional water-source geothermal heat exchange loops, in an interior building/structure. Further, a means of improving the life and reliability of an oil separator for use in a DX system would be of significant importance. Lastly, a means for providing a "mobile" DX system, that not only provided cooling, but that also generated potable water from natural moisture in the air, would also be of value for transient applications, such as for military use and for temporary field office use (such as for temporary oil exploration and/or engineering field office and/or housing facilities, or the like).
Consequently, a means to accomplish at least one of the said primary objectives would be preferable. The present disclosure provides solutions to these preferable objectives, as hereinafter more fully described.

Direct exchange system design improvements


Disclosed and claimed are cocoa extracts such as polyphenols or procyanidins, methods for preparing such extracts, as well as uses for them, especially as antineoplastic agents and antioxidants. Disclosed and claimed are antineoplastic compositions containing cocoa polyphenols or procyanidins and methods for treating patients employing the compositions. Additionally disclosed and claimed is a kit for treating a patient in need of treatment with an antineoplastic agent containing cocoa polyphenols or procyanidins as well as a lyophilized antineoplastic composition containing cocoa polyphenols or procyanidins. Further, disclosed and claimed is the use of the invention in antioxidant, preservative and topiosomerase-inhibiting compositions and methods.

Polyphenols are an incredibly diverse group of compounds (Ferreira et al., 1992) which widely occur in a variety of plants, some of which enter into the food chain. In some cases they represent an important class of compounds for the human diet. Although some of the polyphenols are considered to be nonnutrative, interest in these compounds has arisen because of their possible beneficial effects on health. For instance, quercitin (a flavonoid) has been shown to possess anticarcinogenic activity in experimental animal studies (Deshner et al., 1991 and Kato et al., 1983). (+)-Catechin and (-)-epicatechin (flavan-3-ols) have been shown to inhibit Leukemia virus reverse transcriptase activity (Chu et al., 1992). Nobotanin (an oligomeric hydrolyzable tannin) has also been shown to possess anti-tumor activity (Okuda et al., 1992). Statistical reports have also shown that stomach cancer mortality is significantly lower in the tea producing districts of Japan. Epigallocatechin gallate has been reported to be the pharmacologically active material in green tea that inhibits mouse skin tumors (Okuda et al., 1992). Ellagic acid has also been shown to possess anticarcinogen activity in various animal tumor models (Bukharta et al., 1992). Lastly, proanthocyanidin oligomers have been patented by the Kikkoman Corporation for use as antimutagens. Indeed, the area of phenolic compounds in foods and their modulation of tumor development in experimental animal models has been recently presented at the 202nd National Meeting of The American Chemical Society (Ho et al., 1992; Huang et al., 1992).
However, none of these reports teaches or suggests cocoa extracts, any methods for preparing such extracts, or, any uses as antineoplastic agents for cocoa extracts.
Since unfermented cocoa beans contain substantial levels of polyphenols, the present inventors considered it possible that similar activities of and uses for cocoa extracts, e.g., compounds within cocoa, could be revealed by extracting such compounds from cocoa and screening the extracts for activity. The National Cancer Institute has screened various Theobroma and Herrania species for anti-cancer activity as part of their massive natural product selection program. Low levels of activity were reported in some extracts of cocoa tissues, and the work was not pursued. Thus, in the antineoplastic or anti-cancer art, cocoa and its extracts were not deemed to be useful; i.e., the teachings in the antineoplastic or anti-cancer art lead the skilled artisan away from employing cocoa and its extracts as cancer therapy. Since a number of analytical procedures were developed to study the contributions of cocoa polyphenols to flavor development (Clapperton et al., 1992), the present inventors decided to apply analogous methods to prepare samples for anti-cancer screening, contrary to the knowledge in the antineoplastic or anti-cancer art. Surprisingly, and contrary to the knowledge in the art, e.g., the National Cancer Institute screening, the present inventors discovered that cocoa polyphenol extracts which contain procyanidins, have significant utility as anti-cancer or antineoplastic agents. Additionally, the inventors demonstrate that cocoa extracts containing procyanidins have utility as antioxidants.

Methods of treatment using procyanidin antioxidants


The present invention provides a semiconductor device comprising:

(i) Field of the Invention
The present invention relates to a semiconductor device and a process for production thereof. More particularly, the present invention relates to a fine wiring structure of semiconductor device and a process for production thereof.
(ii) Description of the Prior Art
As the semiconductor elements of semiconductor device become finer, the semiconductor device must have a finer multi-layered wiring structure. Currently, in semiconductor devices having such a multi-layered wiring structure, there is mainly used, as the inter-level isolation film, a silicon oxide-based isolation film of relatively small dielectric constant and stable quality so that the parasitic capacitance between upper-layer wirings and lower-layer wirings and between adjacent wirings in the same wiring layer level can be reduced.
As the semiconductor elements become finer, the wiring width and wiring-to-wiring distance of lower-layer wirings are made smaller; however, in order to avoid an increase in wiring resistance, the wirings in said wiring layer level must have a certain cross-sectional area. As a result, both the aspect ratio of a wiring (wiring height/wiring width) and the aspect ratio between wirings (wiring height/wiring-to-wiring distance) become large. This invites a significant increase in parasitic capacitance between wirings, resulting in (1) reduction in transfer speed of signal and (2) frequent occurrence of cross-talk between wiring layers (occurrence of signal noise between adjacent wirings).
Further, if the inter-level isolation film has a large step in the surface, when an upper wiring layer is formed, it is impossible to form a fine resist pattern by photolithography owing to the shortage of focus margin. Even if it is possible, the above-mentioned difference in surface level gives rise to (1) the wiring disconnection in upper-layer wirings and (2) remaining of unetched wiring material at the sites of level difference. Thus, the inter-level isolation film must have a flat surface.
In order to avoid the above-mentioned problems appearing in a fine multi-layered wiring structure, there have been proposed various techniques of using an inter-level isolation film of low dielectric constant. An example of such techniques is a technique disclosed in Japanese Patent Application Laid-Open No. 55913/1996. This technique is described below with reference to FIG. 7 and FIG. 8, both of which are sectional views showing the key production steps of the wiring structure used in the technique.
As shown in FIG. 7(a), a thick isolation film 101 is formed on a semiconductor substrate. On the thick isolation film 101 are formed a metal layer 102 and a first dielectric layer 103 in this order. On the first dielectric layer 103 is provided a resist mask 104. The first dielectric layer 103 is a highly reliable isolation film made of silicon oxide or the like.
Then, the first dielectric layer 103 and the metal layer 102 are subjected to reactive ion etching (RIE) by using the resist mask 104 as an etching mask. Thereafter, the remaining resist mask 104 is removed. Thus, as shown in FIG. 7(b), wirings 105 of small wiring-to-wiring distance and wirings 106 of large wiring-to-wiring distance are formed on the thick isolation film 101.
Next, as shown in FIG. 7(c), a low-dielectric constant material 107 is applied so as to cover the whole surfaces of the thick isolation film 101, the wirings 105 of small wiring-to-wiring distance, the wirings 106 of large wiring-to-wiring distance and the first dielectric layer 103, followed by levelling of the surface of the applied low-dielectric constant material. As the low-dielectric constant material 107, there is used, for example, a dielectric made of a polymer such as Teflon (trade mark), Parylene (trade mark) or the like.
On the whole surface of the low-dielectric constant material 107 is formed a hard oxide mask 108 as a resist layer. Then, the material 107 and the mask 108 are subjected to selectvie etching. That is, as shown in FIG. 8(a), the low-dielectric constant material 107 and the hard oxide mask 108 both in the region of wirings 106 of large wiring-to-wiring distance are removed and those in the region of wirings 105 of small wiring-to-wiring distance are allowed to remain.
Next, the hard oxide mask 108 on the region of the wirings 105 of small wiring-to-wiring distance is removed. As shown in FIG. 8(b), the low-dielectric constant material 107 is etched back and removed down to a level lower than the upper surface of the first dielectric layer 103 by dry etching. In that case, the first dielectric layer 103 functions as an etching stopper for the low-dielectric constant material 107. Preferably, the low-dielectric constant material 107 is not etched down to a level lower than the top of the wirings 105 of small wiring-to-wiring distance.
Next, as shown in FIG. 8(b), a second dielectric layer 109 is formed by deposition on the whole surface of the resulting material, that is, so as to cover the wirings 106 of large wiring-to-wiring distance, the first dielectric layer 103 and the etched-back low-dielectric constant material 107, then the surface of the second dielectric layer 109 is leveled. The second dielectric layer 109 is an isolation film made of silicon oxide or the like.
As above, on the thick isolation film 101 formed on a semiconductor substrate are formed lower-layer wirings and inter-level isolation films. In that case, a highly reliable isolation film made of silicon oxide or the like is formed in the region of large wiring-to-wiring distance, and a low-dielectric constant material is filled in the region of small wiring-to-wiring distance.
In forming a multi-layered wiring structure (this is not mentioned in the above literature), it is necessary to connect the lower-layer wirings formed by the prior art, with upper-layer wirings. In that case, as shown in FIG. 8(c), throughholes 110 and 110a are formed on a wiring 106 of large wiring-to-wiring distance and a wiring 105 of small wiring-to-wiring distance, respectively. Into the throughholes 110 and 110a are formed metal plugs 111 and 111a, respectively, and the lower-layer wirings and the upper-layer wirings are electrically connected with the metal plugs.
In the prior art as mentioned above, an isolation film of low-dielectric constant is selectively formed in the region of small wiring-to-wiring distance, of the wiring structure of semiconductor device. In this prior art, etching back of low-dielectric constant material 107 is necessary as mentioned with respect to FIG. 8(b). However, in the etching back, the etching-back depth of low-dielectric constant material is very difficult to control. It is also difficult to improve the uniformity of etching-back depth in a semiconductor wafer. Therefore, it is difficult to apply the prior art to production of a semiconductor having a fine wiring structure or using a semiconductor wafer of large diameter (e.g. diameter of 12 in.).
In the prior art, a first dielectric layer 103 and a second dielectric layer 109 are formed on or above both wirings 105 of small wiring-to-wiring distance and wirings 106 of large wiring-to-wiring distance. That is, no low-dielectric constant material 107 is formed on these wirings. Therefore, throughholes can be formed on these wirings. However, if mask alignment is deviated form the predetermined position as shown in FIG. 8(c) in the photolithography employed for throughhole formation, the low-dielectric constant material 107 is also etched in the region of wirings 105 of small wiring-to-wiring distance. When the low-dielectric constant material 107 is made of a polymer having a relative dielectric constant of 3 or less such as mentioned in the above-cited literature, the throughhole 110a formed in the region of wirings 105 of small wiring-to-wiring distance has a very disadvantageous shape. That is, the throughhole extends even to a direction perpendicular to the throughhole axial direction and comes to contain a void, whereby formation of a reliable metal plug 111a is difficult and the resulting semiconductor device has significantly reduced reliability.
The objects of the present invention are to provide a simple process for stably forming a fine wiring structure of semiconductor device; a fine multi-layered wiring structure of high performance and high reliability, of semiconductor device; and a process for forming such a fine multi-layered wiring structure.
According to the present invention, there is provided a semiconductor device comprising:
a semiconductor substrate having semiconductor elements, and
a plurality of wirings formed on the semiconductor substrate via an isolation film,
wherein the wirings are formed in at least one layer level so that the region in which the wirings are formed is divided into a wiring region of small wiring-to-wiring distance and a wiring region of large wiring-to-wiring distance; a first inter-level isolation film is selectively formed in the wiring region of small wiring-to-wiring distance and a second inter-level isolation film is formed in the wiring region of large wiring-to-wiring distance to cover the wirings; throughholes are formed only in the second inter-level isolation film; and the dielectric constant of the first inter-level isolation film is smaller than the dielectric constant of the second inter-level isolation film.
According to the present invention, there is also provided a semiconductor device comprising:
a semiconductor substrate having semiconductor elements, and
a plurality of wirings formed on the semiconductor substrate via an isolation film,
wherein the wirings are formed in at least one layer level so that the region in which the wirings are formed is divided into a wiring region of small wiring-to-wiring distance and a wiring region of large wiring-to-wiring distance; a first inter-level isolation film is selectively formed in the wiring region of small wiring-to-wiring distance, a second inter-level isolation film is formed in the wiring region of large wiring-to-wiring distance to cover the wirings; and a third inter-level isolation film is formed so as to cover the first inter-level-isolation film and the second inter-level isolation film; throughholes are formed only in the second inter-level isolation film and the third inter-level isolation film; and the dielectric constant of the first inter-level isolation film is smaller than the dielectric constants of the second inter-level isolation film and the third inter-level isolation film.
In each of the above semiconductors, it is preferable that the isolation film on the substrate is dented at the surface areas corresponding to the wiring region of small wiring-to-wiring distance but not covered by the wirings of the region and the resulting dents are filled with the first inter-level isolation film.
In each of the above semiconductors, the first inter-level isolation film is constituted by an organic film, an organic SOG film, a polyimide film, a porous inorganic SOG film having a density smaller than that of silicon oxide film, a porous organic SOG film, or a porous organic film, and the second inter-level isolation film is constituted by a silicon oxide film or a silicon oxynitride film.
In each of the above semiconductors, when the wirings are formed in a multi-layered wiring structure, both the lower layer and the upper layer have the above-mentioned wiring structure.
According to the present invention, there is also provided a process for producing a semiconductor device, which comprises:
a step of forming a plurality of wirings on a semiconductor substrate via an isolation film so that the region in which the wirings are formed is divided into a wiring region of small wiring-to-wiring distance and a wiring region large wiring-to-wiring distance, and forming thereon a first inter-level isolation film so as to cover the wirings and then a protective isolation film in this order,
a step of selectively removing the first inter-level isolation film and the protective isolation film present on and in the wiring region of large wiring-to-wiring distance,
a step of forming, by deposition, a second inter-level isolation film on the whole surface of the resulting material and then subjecting the second inter-level isolation film to chemical mechanical polishing with the protective isolation film used as an etching stopper, to obtain a flat surface, and
a step of forming throughholes only in the second inter-level isolation film.
In the above process, the dielectric constant of the first inter-level isolation film is smaller than the dielectric constant of the second inter-level isolation film and the protective isolation film is more resistant to the chemical mechanical polishing than the second inter-level isolation film.
According to the present invention, there is also provided a process for producing a semiconductor device, which comprises:
a step of forming a plurality of wirings on a semiconductor substrate via an isolation film so that the region in which the wirings are formed is divided into a wiring region of small wiring-to-wiring distance and a wiring region large wiring-to-wiring distance, and forming thereon a second inter-level isolation film so as to cover the wirings,
a step of selectively removing the second inter-level isolation film present on and in the wiring region of small wiring-to-wiring distance,
a step of forming, by deposition, a first inter-level isolation film on the whole surface of the resulting material, and then subjecting the first inter-level isolation film to chemical mechanical polishing with the second inter-level isolation film used as an etching stopper to obtain a flat surface, and
a step of forming throughholes only in the second inter-level isolation film.
In the above process, the dielectric constant of the first inter-level isolation film is smaller than the dielectric constant of the second inter-level isolation film and the second inter-level isolation film is more resistant to the chemical mechanical polishing than the first inter-level isolation film.

Semiconductor device having through holes selectively through isolation material covering wirings that are relatively far apart

Abstract: This semiconductor device has a fine multi-layered wiring structure of high performance and remarkably improved reliability.


A process and device for separating different types of particulates from a mixture, which is especially suited for separating unburned carbon from raw fly ash. The process entails separating raw fly ash by size into a fine component and a coarse component (the coarse component having typically higher levels of unburned carbon). The coarse, high carbon, fly ash component (or optionally both components) are processed through an inclined fluidized bed to produce an upgraded coarse component with reduced unburned carbon. An acoustic field is imposed on the inclined fluidized bed(s) in order to enhance the bed's ability to fluidize and segregate the unburned carbon. The upgraded coarse and fine components are then mixed to yield a final product.

In a typical pulverized coal power plant, 80 percent of the ash is carried from the boiler as fly ash and is removed from the flue gas in an electrostatic precipitator, fabric filter or wet scrubber. As a result. U.S. electric utilities spend about $1 billion annually to dispose of most of the 75 million tons of ash removed from their pulverized coal burning plants. For this reason, there has been worldwide activity for many years on the development of ways of utilizing fly ash as an alternative to ash disposal. One of the high volume end uses which has found commercial acceptance is the substitution of fly ash for some of the cement used in concrete.
However, in addition to containing a variety of inert minerals, fly ash may also contain undesirable amounts of unburned carbon. High levels of unburned carbon in fly ash are common with bituminous coals burned in both comer-fired and wall-fired pulverized coal boilers. High levels of unburned coal are even more severe when low NOx burners are used for NOx control. Many utilities who wish to sell their fly ash for use in concrete must reduce these levels of fly ash carbon at high cost. Although over 56 million tons of cement were used to produce concrete in the U.S. in 1991, only approximately 7 million tons of fly ash went into U.S. concrete due to the cost of carbon removal.
One of the standard laboratory tests for the amount of unburned carbon in fly ash is the so-called loss-on-ignition test (LOI). In this disclosure, the terms LOI and unburned carbon will be used interchangeably. The amount of LOI is influenced by the size distribution of coal leaving the coal pulverizers, the combustion conditions in the furnace and the design of he furnace and the burners. For utility boilers burning bituminous coal, utilities have traditionally tried to maintain the LOI in the fly ash to below 6 weight percent. This is done to prevent excessively large losses in boiler efficiency. But for many boilers, this has not been an easy goal to meet. For those utilities who wish to sell their fly ash for use in concrete, it is necessary to maintain the fly ash carbon to even lower levels, with limits of 3 to 5 percent carbon content usually imposed by the concrete manufacturers. Utilities are now installing low NOx burners on their boilers for NOx control. However, as described above, this escalates the problem of fly ash LOI. Test data resulting from recent low NOx installations show that operating a boiler with low NOx burners invariably results in an increase in fly ash LOI, sometimes two-fold in extent.
Thus, there remains a commercial need for an industrial process which beneficiates fly ash in an economical manner, thus making it more amenable to reuse in concrete and otherwise. The problem lies in the separation and removal of carbon from fly ash.
One proposed solution is described in U.S. Pat. No. 5,299,692 issued to Nelson et al. This approach uses an inclined vibrating bed for reducing carbon content. However, this vibratory method was shown to result in 10-80% weight reduction of the carbon content in fly ash. As described above, it is necessary to reduce fly ash carbon to even lower levels on the order of 3 to 5 percent carbon content in accordance with requirements imposed by the concrete manufacturers.
There are analogous methods of particulate separation which have been used for other purposes. For instance, a proven method to achieve separation of pyritic sulfur and ash from the clean portion of coal uses a bubbling fluidized bed operating at room temperature and atmospheric pressure.
FIG. 1 illustrates a bubbling (or gas) fluidized bed 1. At flow rates above minimum fluidization (U.sub.mf), some of the gas flows through the bed from bottom (Z=0) to top (Z=L) in the form of voids of gas or bubbles. As these bubbles move upward through the bed, they cause agitation and motion of the solids, leading to circulation of solid material in the axial direction. When particles of different densities and sizes are contained in the fluidized bed 1, there is a tendency at near minimum bubbling conditions for the solids to stratify in the vertical direction Z according to density, and to a lesser extent, size. When the fluidized bed is used for separating pyritic sulfur and ash from the clean portion of crushed coal, the clean fraction of the coal segregates at the top of the bed, with the liberated coal mineral particles settling towards the bottom. As a consequence, the pyrite content of the coal at the top of the bed (near Z=L) is lowered, thereby permitting recovery of coal with substantially reduced amounts of pyrite. This is shown graphically in FIGS. 2-3, which graphs represent the vertical variation of coal and ash. respectively, after processing in a fluidized bed 1 (as a function of vertical position within the bed).
Specifically, FIG. 2 is a graphical illustration of the local coal concentration (%) as a function of the vertical position Z along the bed 1. It can be seen that the coal concentration increases toward the top of the bed (near Z=L).
FIG. 3 is a graphical illustration of the local ash content of the coal (%) as a function of the vertical position Z along the bed 1. The ash content increases toward the bottom of the bed (near Z=0).
In summary, the clean coal fractions stratify at the top of the bed (Z=L) with the pyrite and ash concentrated toward the bottom (Z=0), and it only remains to separate the clean coal and remove the pyrite and ash concentrations.
An improved continuous process for cleaning coal is disclosed in U.S. Pat. No. 5,197,398. This process, referred to as D-CoP, relies on an inclined fluidized bed (shown in FIG. 4 herein). This type of bed resembles a long, nearly horizontal, table, with fluidizing air passing vertically upward through a distributor causing bubbling to occur in the bed material. The coal and magnetite, which arc added to the bed at one end via coal feed and magnetite feed, flow along the length of the bed, and as they do so, the pyrite and other minerals sink downward through the layer of particles. The clean coal with some magnetite is then separated from the coal refuse at the discharge end. The D-CoP process relies on the use of a bubbling fluidized bed to achieve separation of particles based on differences in density. The bubbles, which are formed at the distributor located at the bottom of the bed, act as pumps. They carry material upward from the bottom of the bed, and at the same time, provide a mechanism by which relatively dense particles near the top of the bed can move downward. Thus, the ability to achieve stable bubbling fluidization is central to the good separation efficiencies which are achieved by D-CoP when used for cleaning coal.
In order to apply this fluidized bed approach to fly ash, it is necessary to achieve good bubbling fluidization. However, fly ash particles are relatively small in size, with mean particle diameters which are typically less than 15 to 20 microns. Particles in this size range do not fluidize well in the bubbling mode. Instead, the particles tend to clump together, causing an unsteady slugging type of fluidization.
In 1994, S. Mori and T. Sawa from Nagoya University in Japan published a paper in Japanese entitled "Development of a Coal Fly Ash Upgrading Process." That paper describes the use of a fluidized bed approach to beneficiate fly ash. However, in the Mori approach, two fluidized beds are used, the first to achieve a size segregation of the fly ash, and the second to process the fine fraction and achieve a density segregation of this material. To deal with the interparticle forces, Mori and Sawa use a mechanically agitated (vibrated) fluidized bed, which is vibrated at a frequency of 25 Hz. The carbon rises towards the top of this mechanically agitated bed and is removed by suction. Mori does not teach the advantages of using an inclined fluidized bed, and the need for mechanical agitatation results in high capital and operating costs.
There remains a need for a viable industrial process to separate materials with particle diameters in this range, and it is herein disclosed how an improved approach for separating, e.g., carbon from fly ash, using an inclined fluidized bed can achieve the desired result.
It is additionally possible to attain even better separation by supplemental acoustic separation.
There has been some previous work on the use of an acoustic field to enhance the fluidization of fine particles. For instance, Chirone et al., Bubbling "Fluidization of a Cohesive Powder in an Acoustic Field," Fluidization VII, Engineering Foundation, (1992), studied bubbling fluidization of a cohesive powder (1 to 45 microns) in an acoustic field. This study reported that the large clusters responsible for the tendency of the powder to spout became converted into fluidizable sub-clusters by the acoustic field, thus making it possible to achieve stable bubbling conditions. Chirone et al. used sound intensity levels in the range of 120 to 150 dB with a frequency of 190 hertz.
Nowak et al., "Fluidization and Heat Transfer of Fine Particles in an Acoustic Field," Fluid-Particles Processes: Fundamentals and Anclications, AIChE Symposium Series No. 296, Volume 89, (1993), found similar beneficial effects of an acoustic field on the fluidization of cohesive powders with sound pressure levels ranging from 100 to 130 DB being required to achieve the desired effect.
To date, there have been no efforts to determine the effect of the acoustic field on those properties of the bubbles which affect solids mixing and segregation.
It would be greatly advantageous to provide an improved industrial process to separate materials with smaller particle diameters such as fly ash using an inclined fluidized bed approach with optional acoustic enhancement. This would allow economical beneficiation of these particulates, thus making them more amenable to reuse (such as fly ash for concrete and other uses).

Fly ash processing using inclined fluidized bed and sound wave agitation


The vehicle for collecting, sorting and reducing the volume of recyclable wastes and regular household and commercial garbage includes a large container with plural compartments mounted to the exterior of the vehicle includes a lifting mechanism for lifting the container to the top of the vehicle so that its contents can be dropped through chutes into plural bins. The lifting mechanism assures that the integrity of the sort of recyclables into each compartment of the container is maintained as the waste drops from the compartments through the chutes into individual bins. Between the chutes and the bins are crushers and shredders for reducing of volume of wastes deposited in the bins. Other wastes are placed in balers for baling. The bales of wastes are stored in a rack under the vehicle""s housing. Crushing, shredding and baling not only reduces volume but allows the vehicle to collect wastes from more homes than without these on-board capabilities. The vehicle may optionally include a section for receiving and processing other organic wastes to reduce its volume.

The present invention relates generally to recycling of household and commercial wastes. In particular, it relates to vehicles for collecting recyclables at curbside or at places of commerce.
As a result of increasing concern for the environment and the efficient use of energy resources, there has been a growing interest in recycling of materials, especially recyclable components of household refuse. Among the types of materials that can be recycled are cardboard, chipboard, magazines, newspaper, plastics, glasses and metals. However, in order to recycle these materials efficiently, they have to be collected and carefully sorted. Recyclables may fall into any one of a dozen different categories. Glass, for example, may be clear, green or brown; plastics may be made of clear polyethylene (PET) or high density polyethylene (HDPE) or mixed plastics. Homeowners and business owners, even when highly motivated to recycle, have difficulty sorting recyclables into all the categories possible.
Another problem with collecting recyclables is the volume of materials. Glass, cardboard, newspaper, chipboard, magazines and plastic bottles are bulky. Metal cans can be crushed to some extent by the homeowner but still occupy a considerable portion of their original volume. Vehicles for transporting materials are limited by both space and weight, but with recyclables, the volume limits are reached well before the weight limits are reached. Each trip to haul wastes where the volume limits are reached well before the weight limits means that the vehicle is not being used effectively. Doubling the amount of weight on a load will significantly improve transportation economics but would have insignificant impact on fuel consumption.
Finally, the economics of recycling in general are fragile. In addition to transportation costs, a major component of costs is the cost of handling. Reducing handling helps to tip the economic factors in favor of recycling and may itself make the difference between a successful recycling program and one that fails.
There have been a number of approaches made to addressing the problem of recycling. The attempts based on having the consumer sort recyclables are impractical because, other than performing a very general sort, consumers are not sensitive to the different kinds of glass, metal, or plastic that need to be segregated. More recently, sorting is being done at a central sorting station. Recyclables are brought there and dumped onto large conveyors where technicians sort through them. The segregated recyclables are then taken to various destinations for reuse. This approach assures that the sorting is done correctly.
Thus there remains a need for a better way to collect and sort recyclables.
The present invention is a vehicle for collecting, sorting and reducing the volume of recyclables. The vehicle has three separate stations for recycling: at one station, eight types of recyclables are sorted by type and crushed and shredded; at the second station, balers are used to bale four types of recyclables; and, at the third, wastes are deposited and, optionally, processed to reduce volume. Altogether, there are twelve categories of recyclable""s that are crushed, shredded and baleed. These include aluminum, bi-metals, three colors of glass, three types of plastics, newspapers, magazines, cardboard and chip board. It is also possible to use the first section to receive cardboard or to bale cans and plastics.
At the first section, a worker or technician sorts the homeowner""s recyclables and possibly regular household wastes into a large container with eight compartments, one compartment for each of the eight primary categories. Between stops and whenever the vehicle is in motion, the container is covered with netting to prevent any recyclables from falling out. Once filled, the container is lifted up the back of the vehicle and part way across the top. As it is moved across the top of the vehicle, a hatch in the roof of the housing is opened allowing the contents of the container to fall into the appropriate bins in the first section of the vehicle. The recyclables fall through chutes to the bins. Each chute is dimensioned to receive the contents of one full compartment of the container. Below the chutes and above the bins are devices that crush or shred the recyclables so that, by the time they fall into the bins, their volume is considerably reduced. After the container is emptied into the chutes, it is moved rearward across the top of the vehicle and back down for re-loading by the technician.
The four categories of baleable waste are taken to the second section of the vehicle, sorted by type into one of four baler bins, and then baleed. When a baler has finished binding each bale, the door to the baler is opened, which automatically kicks the bale out of the baler bin, and then it is dropped from the baling area into a rack that is slung underneath the mid-section of the vehicle.
The third section enables the present vehicle to accept all types of household wastes, including garbage. In a preferred embodiment, the garbage is compacted in the third section or processed in some other way, such as incineration, to reduce its volume.
The combination of volume reduction and sorting in the same vehicle is a major advantage of the present invention. Not only does this permit the vehicle to collect more recyclables before having to return to the central collection station, but it reduces handling. Wastes do not have to be taken from collection bins to crushers and shredders at the central station or at their final destination; rather, they are crushed and shredded when deposited into the bins on the vehicle.
Another feature of the present invention that is important is the combination of balers and crusher/shredders on the same vehicle. This combination means that the present vehicle can collect and prepare all categories of recyclable waste for delivery to their respective recycling facility.
The baler rack is still another feature of the present invention, allowing the baleed waste to be stored on the vehicle, preferably under the baler section out of the way of those operating the baling area.
The various compartments and bins of the present vehicle are dimensioned for collecting residential waste efficiently, another feature of the present invention. Some bins and compartments are larger than others because of variations in the volume of waste of different categories. In general, the bins and compartments are sized for the anticipated volume of waste they are expected to receive.
The closed system of the present invention is a particular feature that it prevents waste particulate created from the volume reduction process from being blown or falling off the vehicle as it goes about its business.
Other features and their advantages will be apparent to those skilled in the art of recycling vehicle design from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings.


Provided are a double wavelength semiconductor light emitting device, having an n electrode and p electrode disposed on the same surface side, in which the area of a chip is reduced to increase the number of chips taken from one single wafer, in which light focusing performance of double wavelength optical beams are improved, and in which an active layer of a light emitting element having a longer wavelength can be prevented from deteriorating in a process of manufacturing; and a method of manufacturing the same.

In recent years, efforts have been focused on developing a short wavelength semiconductor laser for the purpose of its application to high-density optical disk recording and the like. A nitrogen-containing hexagonal compound semiconductor such as GaN, AlGaN, InGaN, InGaAlN and GaPN (hereinafter, simply referred to as a nitride semiconductor) is used for the short wavelength semiconductor laser.
With rapid increase of communication traffic accompanying explosive spread of the Internet, expectations for not only optical communication technologies enabling high-speed and large-capacity communications, but also a high-speed transfer and large-capacity optical disk, and a highly-efficient optical device such as an LED light emitting element have been significantly grown. For example, an element on which two different semiconductor lasers are mounted to support both a CD-Rewritable method and a DVD-Rewritable method, and a double wavelength semiconductor laser to support multiplex communications have actively been developed.
Under these circumstances, as described in Patent Document 1, there is proposed a semiconductor light emitting device in which an n-GaN buffer layer is formed on a substrate; by using this n-GaN buffer layer as a common semiconductor layer, an n-type semiconductor layer, an active layer and a p-type semiconductor layer of each of the double wavelength light emitting elements are laminated on the n-GaN buffer layer; and a p electrode and an n electrode of each light emitting element are disposed opposite to each other across the substrate.
Moreover, a monolithically integrated light emitting element lasing with double wavelengths is manufactured for the semiconductor light emitting device described in the Patent Document 1. Hexagonal nitride semiconductor layers are formed on the main surface of the semiconductor substrate so that the semiconductor lasers have a planar surface parallel to the main surface of the substrate and also have a sloping surface inclined from the main surface, respectively. Subsequently, active layers are epitaxially grown on the planar and inclined surfaces of the semiconductor layers, so that the active layers containing In at composition ratios different from each other are formed to enable laser with double wavelengths.

Double wavelength semiconductor light emitting device and method of manufacturing the same

Abstract: Semiconductor lasers D1 and D2 as two light emitting elements having different wavelengths are integrally formed on a common substrate 1. A semiconductor laminate A is deposited on an n-type contact layer 21 in a semiconductor laser D1, and a semiconductor laminate B is deposited in a semiconductor laser D2. The semiconductor laminate A and semiconductor laminate B are configured to have different layer structures. An n electrode 12 formed between the semiconductor lasers D1 and D2 is shared by the semiconductor lasers D1 and D2, and serves as a common electrode on an n side. Additionally, the semiconductor laminate having a shorter wavelength is crystal-grown firstly.


A method includes setting a contention scheme for an asynchronous bus such that the contention delay of isochronous transactions on the bus is bounded, and establishing an isochronous interface between at least two devices, the isochronous interface supporting an X-T contract. A number of isochronous transactions and corresponding return transactions delivered across the bus is measured during a specified time interval.

1. Field
The invention relates to the field of data transport, and more particularly, to testing isochronous data transport over an asynchronous bus.
2. Background Information
In digital systems, data may be transferred between devices and a shared resource (for example, a memory). The data may be transferred in units known as transactions. A transaction is a collection of information necessary to initiate or complete an operation, such as an operation to read data from memory or write data to memory. A shared bus may be employed for such transactions. The bus may employ various contention strategies, including arbitration rules, to manage concurrent demands for the bus from multiple sources. Of course, regarding references to a bus xe2x80x9chavingxe2x80x9d, xe2x80x9cemployingxe2x80x9d, etc. a contention scheme it should be understood that such contention schemes are typcially provided and enforced by bus controller circuits coupled to the bus, and devices coupled to the bus which cooperate with the bus controller. Arbitration rules commonly depend on some form of priority settings to resolve access contention. One strategy of contention resolution is often referred to as xe2x80x9casynchronousxe2x80x9d. Asynchronous strategies depend more strongly on priorities assigned to contending uses than on timely disposition of individual transactions. A transaction (for example a read or write request) may occasionally encounter long, unpredictable delays while pending transfer over an asynchronous bus.
Buses employing asynchronous contention resolution may be subject to several factors that interfere with timely transfer of transactions. Typically, an entire transaction may be transferred across the bus before control of the bus is relinquished to other transactions. While a transaction is in progress, a pending transaction (one awaiting transfer over the bus) must await the next arbitration opportunity. An arbitration opportunity is a point in time at which the control logic for the bus determines which transaction pending on the bus will be next transferred. Time thus spent is referred to as xe2x80x9ccollision delayxe2x80x9d.
Once the current transaction is ended the pending transaction may encounter further delay. This further delay may result when another transaction is pending with higher priority. This is referred to as xe2x80x9carbitration delayxe2x80x9d.
Once the pending transaction obtains access to the bus, a finite time may elapse before the transaction has been transferred in its entirety across the bus. This is referred to as xe2x80x9ctransmission delayxe2x80x9d. All three types of delay are common in buses employing priority-based contention resolution, i.e. asynchronous buses. The combined effect of these delays may be to render the completion time of a transaction unpredictable and perhaps even unbounded. Many media-oriented devices (audio and video capture and playback devices, for example) may depend on timely transactions for correct operation. Isochronous devices require the transfer of up to a specified maximum amount of data X, via one or more transactions, during each period in a series of time periods of fixed duration T. This requirement (henceforth referred to as the isochronous X-T contract) may be difficult to accomplish in light of the unpredictable delivery times afforded by asynchronous data transfer strategies.
Supporting isochronous devices using an asynchronous bus may be accomplished using various buffering and flow-control techniques. However, many buffering techniques rely upon excessive buffer sizes. These excessive buffer sizes attempt to account for the unpredictable delays inherent with asynchronous buses. Excessive buffering may add undesirable processing delay, cost, and circuit size to components that implement an X-T contract. Flow-control may add unnecessary complexity to such components as well.
Thus, there is a continuing need for circuits which support isochronous data transfer over asynchronous busses. As such circuits are developed, there arises a need for systems and methodologies for thoroughly testing such circuits.
A method includes setting a contention scheme for an asynchronous bus such that the contention delay of isochronous transactions on the bus is bounded, and establishing an isochronous interface between at least two devices, the isochronous interface supporting an X-T contract. A number of isochronous transactions and corresponding return transactions delivered across the bus is measured during a specified time interval.

Method and apparatus to test an isochronous data transport


An evaporation supply apparatus for raw material used in semiconductor manufacturing includes a source tank in which a raw material is pooled; a flow rate control device that supplies carrier gas at a regulated flow rate into the source tank; a primary piping path for feeding mixed gas G0, made up of raw material vapor G4 and carrier gas G1, an automatic pressure regulating device that regulates a control valve based on the detected values of the pressure and temperature of mixed gas G0 to regulate the cross-sectional area of the passage through which the mixed gas G0 is distributed so as to hold the pressure of the mixed gas G0 inside the source tank constant; and a constant-temperature heating unit for heating the source tank to a set temperature, in which mixed gas G0 is supplied to a process chamber while controlling the pressure inside the source tank.

As shown in FIG. 9, conventionally, when manufacturing semiconductors to form an epitaxial thin film by the MOCVD method, carrier gas G1 such as H2 is fed into a pool of raw material 4 in a source tank 5. The liquid-state raw material 4 is stirred by foaming and the raw material 4 is brought into contact with the carrier gas G1 which, at a predetermined temperature, promotes the generation of saturated vapor G4 from the raw material 4. Mixed gas G0, made up of the saturated vapor G4 from the raw material 4 combined with the carrier gas G1, is fed into process chamber 11. FIG. 9 shows a liquid-state raw material (for example, an organometallic compound) 4 pooled inside the source tank 5. However, it is also common to use a solid raw material 4 carried by a porous supporting member located inside the source tank 5 and gas (raw material vapor G4) sublimated from the solid raw material 4.
In FIG. 9, reference numeral G1 represents a carrier gas; G4 represents a saturated vapor of a raw material; G0 represents a mixed gas; 1 designates a carrier gas source (container) such as hydrogen; 2 designates a decompressor; 3 designates a mass flow control device; 4 designates a raw material; 5 designates a source tank; 6 designates a constant temperature reservoir; 7 designates an inlet valve; 8 designates a lead-in tube; 9 designates an outlet valve; 10 designates a valve; 11 designates a process chamber (a crystal growth furnace); 12 designates a heater; 13 designates a substrate; and 14 designates a vacuum pump.
In the apparatus shown in FIG. 9, using a system in which pressure control of the temperature of the constant temperature reservoir 6 (which controls the saturated vapor G4 of the raw material 4) and flow rate control of the carrier gas G1 are superimposed allows the supply amount of the raw material 4 (an epitaxial raw material) to the process chamber 11 to be controlled. However, it proves difficult to highly accurately control the mixture ratio between gases G1 and G4 or the supply flow rate of the mixed gas G0. As a result, variation may easily occur in film thickness or film composition, and thus, the properties of the manufactured semiconductor are not stabilized, which results in the drawback of a lack of consistency.
In the evaporation supply apparatus shown in FIG. 9, in order to achieve highly accurate flow rate control of the mixed gas G0, the pressure of the vapor G0 inside the source tank 5 must be held at a constant set value at all times. However, in the conventional evaporation supply apparatus shown, in the supply system that supplies mixed gas to process chamber 11, only valves 9 and 10 are included, and little consideration is given to this point of the process. As a result, the highly accurate control of the supply amount of the mixed gas G0 is significantly difficult.
To solve this problem, as shown in FIG. 10, a control system for the raw material supply amount has been developed in which the supply system of the raw material vapor G4 and the supply system of the carrier gas G1 are completely separated so that control of the supply amount of the raw material vapor G4 and control of the supply amount of the carrier gas G1 are independently performed. This system has already been put into practical use. In FIG. 10, reference numerals 3a and 3b denote mass flow control devices; 12 denotes a heater; 17 denotes an constant air temperature reservoir; and 18 denotes a mixture unit.
In the control system in FIG. 10, use of a plurality of mass flow control devices 3a and 3b results in two flow rate control systems. Thus, the evaporation supply apparatus is complicated and large, and obtaining a uniform mixture of carrier gas G1 and vapor G4 in the mixture unit 18 is difficult. As a result, it has gradually become apparent that in terms of stability of the properties of a manufactured semiconductor, there is no significant difference between the evaporation supply apparatuses shown in FIG. 9 and FIG. 10.
Further, in recent years, in this type of evaporation supply apparatus, in order to implement a further downsizing of the apparatus and an increase in raw material supply amount, there has been a strong demand to increase the pressure of the raw material vapor G4 and to more highly accurately control the mixture ratio between the carrier gas G1 and the vapor G4 and the supply amount thereof.
In the evaporation supply apparatuses shown in FIG. 9 and FIG. 10, it is difficult to respond to the demand to downsize the evaporation supply apparatus, increase in vapor supply amount, and control of the mixture ratio and the mixed gas supply amount with high accuracy.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2611008    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2611009    [Patent Document 3] Japanese Utility Model Registration No. 2600383

Evaporation supply apparatus for raw material and automatic pressure regulating device used therewith


Disclosed is a method and apparatus for automatically backing up a Home Agent in Mobile IP. The method employs important components of the widely-used Hot Standby Router Protocol, but extends it to include synchronization of the mobility binding table between an active Home Agent and a standby Home Agent that backs it up. Also disclosed is a more general protocol for extending HSRP and related redundancy protocols to synchronize higher level functions other than mobility binding lists in Mobile IP (e.g., address translation tables in Network Address Translation (NAT), address bindings in Dynamic Host Configuration Protocol (DHCP) servers, dynamic ACL in Reflexive Access List, and TCP and GTP layer context in GPRS support nodes: SGSN and GGSN). Still other protocols that could benefit from HSRP include Lock and Key, Context-Based Access List, IP Security (IPSec), and H.323 gatekeeper.

This invention relates to Mobile IP network technology. More particularly, the invention relates to redundancy protocols and apparatus for protecting a Mobile IP system from failure due to the loss of a Home Agent (xe2x80x9cHAxe2x80x9d) or Foreign Agent (xe2x80x9cFAxe2x80x9d).
Mobile IP is a protocol which allows laptop computers or other mobile computer units (referred to as xe2x80x9cMobile Nodesxe2x80x9d herein) to roam between various sub-networks at various locationsxe2x80x94while maintaining internet and/or WAN connectivity. Without Mobile IP or related protocol, a Mobile Node would be unable to stay connected while roaming through various sub-networks. This is because the IP address required for any node to communicate over the internet is location specific. Each IP address has a field that specifies the particular sub-network on which the node resides. If a user desires to take a computer which is normally attached to one node and roam with it so that it passes through different sub-networks, it cannot use its home base IP address. As a. result, a business person traveling across the country cannot merely roam with his or her computer across geographically disparate network segments or wireless nodes while remaining connected over the internet. This is not an acceptable state-of-affairs in the age of portable computational devices.
To address this problem, the Mobile IP protocol has been developed and will soon be implemented. An implementation of Mobile IP is described in RFC 2002 of the Network Working Group, C. Perkins, Ed., October 1996. Mobile IP is also described in the text xe2x80x9cMobile IP Unpluggedxe2x80x9d by J. Solomon, Prentice Hall. Both of these references are incorporated herein by reference in their entireties and for all purposes.
The Mobile IP process and environment are illustrated in FIG. 1A. As shown there, a Mobile IP environment 2 includes the internet (or a WAN) 4 over which a Mobile Node 6 can communicate remotely via mediation by a Home Agent 8 and a Foreign Agent 10. Typically, the Home Agent and Foreign Agent are routers or other network connection devices performing appropriate Mobile IP functions as implemented by software, hardware, and/or firmware. A particular Mobile Node (e.g., a laptop computer) plugged into its home network segment connects with the internet through its designated Home Agent. When such Mobile Node roams, it communicates via the internet through an available Foreign Agent. Presumably, there are many Foreign Agents available at geographically disparate locations to allow wide spread internet connection via the Mobile IP protocol. Note that it is also possible for the Mobile Node to register directly with its Home Agent.
As shown in FIG. 1A, Mobile Node 6 normally resides on (or is xe2x80x9cbased atxe2x80x9d) a network segment 12 which allows its network entities to communicate over the internet 4 through Home Agent 8 (an appropriately configured router denoted R2). Note that Home Agent 8 need not directly connect to the internet. For example, as shown in FIG. 1A, it may be connected through another router (a router R1 in this case). Router R1 may, in turn, connect one or more other routers (e.g., a router R3) with the internet.
Now, suppose that Mobile Node 6 is removed from its home base network segment 12 and roams a remote network segment 14. Network segment 14 may include various other nodes such as a PC 16. The nodes on network segment 14 communicate with the internet through a router which doubles as Foreign Agent 10. Mobile Node 6 may identify Foreign Agent 10 through various solicitations and advertisements which form part of the Mobile IP protocol. When Mobile Node 6 engages with network segment 14, Foreign Agent 10 relays a registration request to Home Agent 8 (as indicated by the dotted line xe2x80x9cRegistrationxe2x80x9d). The Home and Foreign Agents may then negotiate the conditions of the Mobile Node""s attachment to Foreign Agent 10. For example, the attachment may be limited to a period of time, such as two hours. When the negotiation is successfully completed, Home Agent 8 updates an internal xe2x80x9cmobility binding tablexe2x80x9d which specifies the Foreign Agent""s IP address in association with the identity of Mobile Node 6. Further, the Foreign Agent 10 updates an internal xe2x80x9cvisitor tablexe2x80x9d which specifies the Mobile Node address, Home Agent address, etc. In effect, the Mobile Node""s home base IP address (associated with segment 12) has been shifted to the Foreign Agent""s IP address (associated with segment 14).
Now, suppose that Mobile Node 6 wishes to send a message to a corresponding node 18 from its new location. An output message from the Mobile Node is then packetized and forwarded through Foreign Agent 10 over the internet 4 and to corresponding node 18 (as indicated by the dotted line xe2x80x9cpacket from MNxe2x80x9d) according to a standard internet protocol. If corresponding node 18 wishes to send a message to Mobile Nodexe2x80x94whether in reply to a message from the Mobile Node of for any other reasonxe2x80x94it addresses that message to the IP address of Mobile Node 6 on sub-network 12. The packets of that message are then forwarded over the internet 4 and to router R1 and ultimately to Home Agent 8 as indicated by the dotted line (xe2x80x9cpacket to MN(1)xe2x80x9d). From its mobility binding table, Home Agent 8 recognizes that Mobile Node 6 is no longer attached to network segment 12. It then encapsulates the packets from corresponding node 18 (which are addressed to Mobile Node 6 on network segment 12) according to a Mobile IP protocol and forwards these encapsulated packets to a care of address for Mobile Node 6 as shown by the dotted line (xe2x80x9cpacket to MN(2)xe2x80x9d). The C.O. address is the IP address of Foreign Agent 10. Foreign Agent 10 then strips the encapsulation and forwards the message to Mobile Node 6 on sub-network 14. The packet forwarding mechanism implemented by the Home and Foreign Agents is often referred to as xe2x80x9ctunneling.xe2x80x9d
FIG. 1B illustrates a significant problem with the Mobile IP system 2. If Home Agent 8 fails or otherwise become inoperative (due to a power failure, rebooting, scheduled maintenance. etc.), Mobile Node 6 is left without the ability to (1) receive new internet messages addressed to it at network segment 12 and (2) register with other Foreign Agents. In effect, Mobile Node 6 is cut-off from internet connection when Home Agent 8 goes down. This problem may extend to other Mobile Nodes supported by Home Agent 8. Often, a given Home Agent will be responsible for servicing numerous Mobile Nodes which may be based at sub-network 12.
As shown in FIG. 1B, when Home Agent 8 fails, not only is network segment 12 disconnected from the internet, but Mobile Nodes at remote locations are also blocked from the registration and packet receipt functions of Mobile IP. In some networks, there may be other routers connecting segment 12 to the internet. Such additional routers would allow fixed hosts on the segment to maintain their internet connections but would not allow remote access to Mobile Nodes. Similarly, if Foreign Agent 10 should fail, all Mobile Nodes visiting sub-network 14 lose connections, even though there may be other routers on that sub-network.
A redundancy protocol known as Hot Standby Router Protocol (xe2x80x9cHSRPxe2x80x9d) is widely used to back up primary routers for a network segment. In HSRP, a xe2x80x9cstandbyxe2x80x9d or xe2x80x9csecondaryxe2x80x9d router is designated as the back-up to an xe2x80x9cactivexe2x80x9d or xe2x80x9cprimaryxe2x80x9d router. The standby router is linked to the network segment or segments serviced by the active router. The active and standby routers share a xe2x80x9cvirtual IP addressxe2x80x9d and possibly a xe2x80x9cvirtual Media Access Control (MAC) address.xe2x80x9d All internet communication to and from the relevant sub-network employs the virtual IP and MAC addresses. At any given time, the active router is the only router adopting the virtual addresses. Then, if the active router should cease operation for any reason, the standby router immediately takes over its load (by adopting the virtual addresses). Further details of HSRP can be found in RFC 2281, xe2x80x9cCisco Hot Standby Router Protocol (HSRP)xe2x80x9d by T. Li, B. Cole, P. Morton, and D. Li and in U.S. Pat. No. 5,473,599 issued to Li and Cole on Dec. 5, 1995. Both of these references are incorporated herein by reference in their entireties and for all purposes.
If Home Agent 8 participated in a hot standby router protocol (together with other routers connected to segment 12), its failure would allow those nodes currently plugged into sub-network 12 to maintain their communications with internet 4. However, its failure would leave Mobile Node 6 stranded on network segment 14. HSRP has no mechanism for handling internet communications via Mobile IP. This is partly due to the fact that in Mobile IP it is not enough to simply have a standby router ready to take over as active router. The Home Agent (active router) must carry-out higher level functions required by Mobile IP such as keeping track of the locations (and associated Foreign Agents) of the various Mobile Nodes for which it is responsible. Similarly, a Foreign Agent must keep track of visiting Mobile Nodes and their associated Home Agents.
One redundancy mechanism for Mobile IP has been proposed. It goes by the acronym HARP which stands for Home Agent Redundancy Protocol. It was presented in an Internet Engineering Task Force memo of Chambless and Binkley entitled xe2x80x9cHome Agent Redundancy Protocolxe2x80x9d and having a URL of ftp://ietf.org/internet-drafts/draft-chambless-mobileip-harp00.txt. This protocol provides for a redundant or xe2x80x9cpeerxe2x80x9d Home Agent which is intended to contain a record of the Mobile Node locations stored in the primary Home Agent. While this proposed protocol does provide a redundancy mechanism for Mobile IP Home Agents, it has certain short comings. Notably, it does not make use of a widely installed redundancy protocol such as HSRP. Therefore, to implement HARP, many enterprises must undertake a rather significant change to its existing network solution. More importantly, HARP is concerned only with Mobile IP. Many other network functions such as Network Address Translation (xe2x80x9cNATxe2x80x9d), IP security, Reflexive Access List, etc. all could profit from router redundancy. However, each of these has its own specific high level requirements (analogous to the mobility binding table required for Mobile IP). HARP cannot be easily extended to these Non-Mobile IP network functions.
For the above reasons, an improved Home Agent redundancy protocol is required for Mobile IP.
The present invention provides a method and apparatus for automatically backing up a Home Agent or a Foreign Agent in Mobile IP. The invention employs important components of the widely-used Hot Standby Router Protocol, but extends it to include synchronization of the mobility binding table (or a visitor table in the case of a foreign agent) between an active Mobility Agent and a standby Mobility Agent that backs up the active Mobility Agent. Note that a xe2x80x9cMobility Agentxe2x80x9d may be either a Home Agent or a Foreign Agent. The invention also provides a more general protocol for extending HSRP and related redundancy protocols to synchronize higher level dynamic functions other than mobility binding lists in Mobile IP (e.g., address translation tables in Network Address Translation (NAT), address bindings in Dynamic Host Configuration Protocol (DHCP) servers, dynamic ACL in Reflexive Access List, and TCP and GTP layer context in GPRS support nodes: SGSN and GGSN). Still other protocols that could benefit from HSRP include Lock and Key, Context-Based Access List, IP Security (IPSec), and H.323 gatekeeper.
One aspect of the invention provides a method of operating a standby Mobility Agent to provide Mobile IP redundancy. The method may be characterized as including the following sequence: (a) determining that an active Mobility Agent, with which the standby Mobility Agent shares a virtual IP address known to a Mobile Node, is no longer acting as a Mobility Agent for the Mobile Node; (b) assuming the role of active Mobility Agent for the shared virtual IP address, thereby handling a registration from the Mobile Node; and (c) sending a list of registrations currently handled by the active Mobility Agent to a new standby Mobility Agent. The standby Mobility Agent may determine that the active Mobility Agent is no longer acting as a Mobility Agent by various mechanisms. In one case, it receives a resign message from the active Mobility Agent. In another case, it determines that no hello message has been received from the active Mobility Agent within a predefined length of time. In yet another case, the standby Mobility Agent preempts the active Mobility Agent when it determines that it has a higher priority than the active Mobility Agent. When it takes over as active Mobility Agent, it adopts the virtual IP address and, preferably, a virtual MAC address as well.
While operating in its standby capacity, the standby Mobility Agent periodically receives registration entries from the active Mobility Agent by UDP, for example. When this occurs, the standby Mobility Agent adds the registration entries to its own mobility binding table (or visitor table), thereby keeping synchronized with the active Mobility Agent. And when the standby Mobility Agent initially assumes that status, it will receive an entire mobility binding table (or visitor table) specifying multiple registration entries from the active Mobility Agent.
In some embodiments, both the active and standby Mobility Agents will be able to tunnel packets or receive tunneled packets (in the case of Foreign Agents). However, the handling of new registrations will generally be left solely to the active Mobility Agent.
Another aspect of the invention provides a method of maintaining Mobile IP redundancy by the operation of an active Mobility Agent. This method may be characterized by the following sequence: (a) registering a Mobile Node; (b) creating a registration entry internally for the Mobile Node; and (c) sending a message (preferably unicast) notifying a standby Mobility Agent of the registration. In its active capacity, the active Mobility Agent periodically sends hello messages to the standby Mobility Agent, thereby notifying the standby Mobility Agent that the active Mobility Agent continues to function as the active Mobility Agent. The active Mobility Agent may also periodically send hello messages to a standby group of routers, each configured to act as an active Mobility Agent, thereby notifying the standby group that the active Mobility Agent continues to function as the active Mobility Agent. Still further, the active Home Agent may send a resign message to the standby Mobility Agent before resigning the post of active Mobility Agent.
The active Mobility Agent may also receive a request from the standby Mobility Agent to dump an entire mobility binding table (or visitor table) containing multiple registration entries from the active Mobility Agent to the standby Mobility Agent. When this occurs, the active Mobility Agent complies by dumping its mobility binding table (or visitor table) to the standby Mobility Agent, preferably via UDP.
Another aspect of the invention provides a network device (e.g., a router) which implements a generic method of providing redundancy for a network segment. The method synchronizes a dynamic function between an active and a standby device. It may be characterized by the following sequence: (a) assuming the status of standby router to backup an active router, with which the standby router shares a virtual IP address known to a host based at the network segment; (b) determining that the active router is no longer acting as an active router for the host; (c) assuming the role of active router for the shared virtual IP address, thereby handling packet exchange tasks for the host; and (d) apprising a new standby router of an entry to a dynamic list specifying the status of one or more hosts based at the network segment. Preferably, the updating is performed via UDP. Depending upon the function being backed up, the dynamic list may specify various items pertaining to the network status. For example, it may specify a registration for a Mobile IP Mobile Node, an address translation for a network node employing Network Address Translation, etc.
Still another aspect of the invention provides a router supporting Mobile IP. The router may be characterized as including the following features: (a) a memory; (b) a processor coupled to the memory; (c) one or more interfaces for sending and receiving data packets on a network. In this router, the memory and the processor are adapted to provide (a) a primary router address and (b) a group virtual address which is adopted by the router when it becomes the active Mobility Agent of the network segment, and wherein the memory and the processor are adapted to (c) send registration updates to a standby Mobility Agent from among the plurality of routers. The memory and processor are further adapted to assume a status of standby Mobility Agent for backing up the active Mobility Agent. Preferably the router also includes a priority specifying the router""s relative likelihood of becoming the active Mobility Agent in comparison to other routers in the network segment.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following descriptions of the invention in conjunction with the figures.

Mobile IP mobility agent standby protocol


A collectable item system for attachment to a container closure device and a method for distributing collectable items. The collectable item system includes a novelty object having a cavity area therein. A retainer is disposed in the cavity area of the novelty object and is fixedly attached to the novelty object. The retainer includes a pawl edge for engaging a detent area of a container closure device.

Collectables and novelty items, especially collectable items licensed by sports teams are highly prized objects. Accordingly, consumer products manufacturers are continually using licensed products from movies, sports teams and the like to promote their products. Containers for food items and beverages may be used to distribute collectable items that are integral with the container closures. However, because of the many types of closures for food and beverage containers, collectable items must be specifically designed for each of the containers. The wide variety of container designs leads to a large inventory of collectable items of various designs that are needed for attaching to such containers.
Another disadvantage of having collectable items integral with the closure for containers is that the collectable item must be installed on the container at the time the container is filled. When the demand for the collectable item is greater or less than the demand for the product in the container, it difficult to adjust inventories of the product and collectable item as demand changes.
Accordingly, there remains a need for a simplified system for attaching and distributing collectable items on food and beverage containers that will enable more efficient distribution of the product and collectable items.
With regard to the foregoing, and other objects and advantages, the disclosure provides a collectable item system for attachment to a container closure device and a method for distributing collectable items. The collectable item system includes a novelty object having a cavity area therein. A retainer is disposed in the cavity area of the novelty object and is fixedly attached to the novelty object. The retainer includes a pawl edge for engaging a detent area of a container closure device.
In another embodiment, the disclosure provides a method for distributing collectable items. The method includes the steps of providing a collectable item comprising a miniature sports object having a cavity area therein. The collectable item is attached to a retainer so that the retainer is disposed in the cavity area of the sports item. The retainer includes a projection adjacent one end thereof for engaging a detent area of a container closure device. The sports item and retainer are engaged with the closure device of a consumer container. The consumer container containing the collectable item is then distributed to consumers.
A further embodiment of the disclosure provides a multi-part collectable item system for a beverage container. The multi-part collectable item system includes a miniature replica of a collectable object having a cavity area therein. A retainer is disposed in the cavity area of the collectable object and is attached to the collectable object. The retainer includes a pawl edge for engaging a detent area of a closure device for the beverage container.
An advantage of embodiments of the disclosure is that a system for attaching collectable items to a wide variety of containers may be provided using a relatively small inventory of collectable items. The system described herein enables a collectable item to be applied to a container for a food or beverage before or after leaving the container filling facility. Hence, as the demand for the product or collectable item changes, inventories may be more readily adjusted to meet the changing demands since the collectable items do not have to be attached to the containers at the time the containers are filled with the products.


The preferred embodiments of the present invention provide a system and method for reducing the battery power required by a handheld device (300) that incorporates a graphical display (301). Graphical display (301), display drivers (307), LCD controller (403) and a memory (405) are optimized such that several pixels of information may be clocked simultaneously when the device is operating in a partial display mode. The optimized circuitry reduces the required refresh clock frequency (411) and thus the current drain on a device battery (319) thereby improving device operation time.

Many handheld devices, such as personal digital assistants (PDAs), wireless telephones, cellular telephones, and laptop computers, incorporate graphical displays. Because these devices operate on battery power, they are constrained to a limited time of operation based on battery drain. Some device displays may cause a drain on the battery even when the device is not fully in use. For example, the typical handheld device has a means of indicating a status, such as whether the device is on or off. Additionally, the display may provide an indication of received radio signal strength from a network, and battery charge status. Recent models of mobile telephones employ graphical displays that incorporate all or more such indications as standard regardless of whether the phone is fully powered or in stand-by mode. Because the graphical display requires battery power to maintain standard indications, the battery charge time and thus operation time of the mobile device is inconveniently reduced.
Various techniques can be used to reduce battery drain due to a device display. One such technique is to define a partial display area, such that when user input is not present for some period of time, only a portion of the display receives power.
Another technique is to reduce the color depth of the displayed pixels. Normally, for a full graphical display, several bits are utilized to define each basic spectral color per pixel. However, when a device is in a stand-by mode, it is not necessary to provide a full-color depth. In stand-by mode, a reduced number of colors could be used such that fewer bits per basic spectral color are required. This reduced number of bits reduces battery drain by lowering the power required to refresh the display.
Although techniques such as partial display and reduced color depth help reduce battery drain by the display, other elements within a handheld device associated with the display also require battery power. For example, none of the techniques address the power consumed by graphic display buffers or other similar memory elements required to maintain the display in standby mode.
Therefore, a need exists for reducing the battery drain due to other elements of the display circuitry, when the device display is in a stand-by mode or partial display mode.

Reduced power consumption for a graphics accelerator and display


A bi-directional VLAN bridging path is created on an edge switch in an MVRP environment without administrator intervention using a virtual network profile (VNP) feature running on the edge switch. The VNP feature is configured to detect a device coupled to a port of the edge switch, learn the Medium Access Control (MAC) address of the device on a MVRP-VLAN and automatically convert the MVRP-VLAN to a VNP-Dynamic-VLAN corresponding to a static VLAN to create a bi-directional VLAN Port Association (VPA) for the device.

1. Technical Field of the Invention
This invention relates generally to data networks and in particular to virtual local area networks.
2. Description of Related Art
Data networks allow many different computing devices, for example, personal computers, IP telephony devices or servers to communicate with each other and/or with various other network elements or remote servers attached to the network. For example, data networks may comprise, without limitation, Metro Ethernet or Enterprise Ethernet networks that support multiple applications including, for example, voice-over-IP (VoIP), data and video applications. Such networks regularly include many interconnected nodes, commonly known as switches or routers, for routing traffic through the network.
The various nodes are often distinguished based on their location within particular areas of the network, commonly characterizing two or three "tiers" or "layers," depending on the size of the network. Conventionally, a three tier network consists of an edge layer, an aggregation layer and a core layer (whereas a two tier network consists of only an edge layer and core layer). The edge layer of data networks includes edge (also called access) networks that typically provide connectivity from an Enterprise network or home network, such as a local area network, to a metro or core network. The edge/access layer is the entry point of the network, i.e., to which the customer network is nominally attached, and the switches residing at the edge layer are known as edge switches. Different types of edge networks include digital subscriber line, hybrid fiber coax (HFC), fiber to the home, and enterprise networks, such as campus and data center networks. Edge switches may perform, for example, L2 switching functions for the attached devices. The edge switches are generally connected to one or more Enterprise switches, Enterprise servers and/or other end devices in the customer network, and may also be connected to an aggregate layer that terminates access links coming from multiple edge switches. Switches residing at the aggregation layer are known as Aggregation Switches. Aggregation Switches may perform, for example, L2 switching and L3 routing of traffic received via the aggregate links from the edge switches. The aggregate layer (in a "three tiered" network) or the edge layer (in a "two tiered" network) is connected to a metro or core network layer that performs Layer 3/IP routing of traffic received from the Aggregation Switches or from edge switches. As will be appreciated, switches at each incremental layer of the network typically have larger capacity and faster throughput.
Virtual Local Area Network (VLAN) technology has allowed Enterprise networks to extend their reach across the core network to enable a LAN to be partitioned based on functional requirements, while maintaining connectivity across all devices on the LAN. However, in order for VLAN's to forward data to the correct destination, all switches (edge and core) in the VLAN should contain the same information in their filtering databases. The IEEE 802.1ak Multiple VLAN Registration Protocol (MVRP) supports dynamic registration of VLAN's on all ports in a VLAN bridged network. In particular, MVRP allows VLAN membership information to be propagated to all ports that are a part of the active topology of the VLAN.
For example, when a VLAN is created on one of the edge switches, MVRP enables the VLAN to be propagated to all of the other edge/core switches in the Ethernet network, which creates a VPA (VLAN Port Association) on the ingress path to each edge/switch. Since VPA's are created only on the ingress of a particular edge switch, in order to provide a bi-directional path for data transfer to/from one or more customer devices in that VLAN that are coupled to that particular edge switch, an administrator can manually configure the edge switch by converting the MVRP-VLAN on the edge switch to a standard (static) VLAN. Once converted, the VLAN is propagated back in the reverse direction, creating VPA's on the reverse path and resulting in a complete VLAN path.
MVRP works well for traditional physical customer devices that are tied to a specific port or switch. However, many Enterprise networks have begun utilizing "Virtual Machines (VMs)" to emulate physical network devices for various purposes, such as testing/debugging, system backup, virtual desktops, on-demand applications and process mobility. Since Virtual Machines are mobile and can potentially move to different edge switches, administrator intervention would be required on each edge switch where the Virtual Machine moves to manually convert the MVRP-VLAN's on those switches to static VLAN's. Manually configuring switches in the Ethernet network based on current locations of VM's requires extensive labor and time, thus increasing the cost of managing VLAN's.
Accordingly, there is a need for systems and methods for creating a VLAN bridging path for Virtual Machines (VMs) within an MVRP environment without the need for administrator intervention.

VLAN bridging path for virtual machines in MVRP environment without administrator intervention


Seal plates are typically mounted over stringer-receiving openings in aircraft ribs. A sealing tool for sealing a stringer-receiving opening in an aircraft rib is disclosed. The sealing tool includes a seal member arranged to seal a gap formed by the opening between the stringer and the rib. An intermediate member is configured to be adjustably mounted on the rib. The adjustable member receives and aligns the seal member over the gap.

Aircraft wings are typically formed with a wing assembly comprising a pair of spars extending in a spanwise direction, and with a plurality of ribs extending in a chordwise direction. The ribs extend between the spars. A skin comprising lower and upper covers extends over the lower and upper sides of the spars and ribs.
Fuel in an aircraft is typically stored in one or more fuel tanks or sealed compartments located in the interior space of the wings and fuselage of the aircraft. The fuel tanks or sealed compartments are defined by structural components of the aircraft assembly. The boundary of such a fuel tank or sealed compartment may be at least partially defined by the spanwise extending spars, a pair of sealed ribs and the lower and upper covers.
A plurality of stringers are disposed on an inner surface of the skin and act to stiffen the skin. The stringers extend in the spanwise direction. As such, the stringers typically extend through the plurality of ribs. Cut-outs, acting as rib openings, are formed at the edges of the ribs through which the stringers extend. The cut-outs are provided with dimensions greater than those of the stringer to be received to account for tolerance build-up during manufacture and assembly of components.
To form sealed ribs, seal plates are typically provided to seal the cut-outs formed in the ribs. Each seal plate is fastened to the rib and extends over the opening to lie adjacent to the stringer extending therethrough. A bead of sealant provides a liquid tight joint between the sealing plate and the stringer to restrict the flow of fuel through the cut-out. With a known arrangement, each cut-out is sealed by a pair of seal plates, one on each side of the stringer.
Seal plates are manually installed from inside the fuel tank following assembly of the covers with the ribs. Seal plates are required to cover and seal the cut-outs. However, installation of the seal plates in an assembled fuel tank is difficult and time consuming.

Sealing tool for sealing an opening in an aircraft rib