A scene is reconstructed by receiving pulses transmitted by a virtual array of transducers. The pulses are reflected by the scene. The virtual array has a set of configurations subject to positioning errors. Each received pulse is sampled and decomposed to produce frequency coefficients stacked in a set of linear systems modeling a reflectivity of the scene. There is one linear system for each configuration. A reconstruction method is applied to the set of linear systems. The reconstruction method solves each linear system separately to obtain a corresponding solution. The corresponding solutions share information during the solving. Then, the solutions are combined to reconstruct the scene.

A typical prior art sensing system uses single-frequency (narrowband) transducers and time delay estimation to determine distances to locations in a scene. Frequently, the narrowband pulses have a center frequency around 40 kHz and bandwidth of 1-2 kHz, i.e., e.g., the pulses operate in the range of 40 kHz±1 kHz.
Specifically, the systems measure a time delay between transmitted and received pulses. The time delay is multiplied by the speed of the pulses to estimate of the distances to the scene.
Additional information can be obtained by an array of transducers (transmitters and receivers), which transmit the same frequency pulse from each transducer with an appropriate time delay between pulses from different transducers, so that the overall transmission is essentially directed towards a particular location in the scene. This is sometimes called beam steering.
By scanning in different directions, the array can estimate the distances to different locations in the scene. That approach is similar to methods used in medical ultrasound. That approach requires a large number of transducers, or different transducers locations to make an effective array. Furthermore, that scanning approach requires multiple pulse transmissions, one for each direction of the beam, which increases the time before the scene can be sufficiently reconstructed. Also, it is not straightforward to form a virtual, array by moving the array elements because the array moves.

Method and system for reconstructing scenes using virtual arrays of transducers and joint sparsity models

Mitsubishi Electric Research Laboratories, Inc.


A linear fresnel solar power system which is transportable in a goods container, wherein the solar power system comprises: a number of rows of reflective mirrors, and a support structure, the support structure comprising a base for assembling the support structure on a commercial goods container, and the container defining a volume, wherein the support structure further comprises: two foldable lateral platforms articulated to the base of the support structure; and two mirror-carrying banks, supported by the lateral platforms, wherein the rows of reflective mirrors are mounted on the mirror-carrying banks. The invention helps to save transportation and assembling costs.

A linear fresnel solar power system is made up of rows of flat or semi-flat mirrors placed next to one another on the same plane. These rows of mirrors have the freedom of movement to rotate around themselves, such that they may perform solar tracking, being oriented at different angles depending on the sun's position. The solar energy reflected by the mirrors hits a linear receiver located at a given height over the plane of the mirrors. The total surface area of the rows of mirrors is significantly greater than the exposed surface area of the linear receiver; consequently, solar radiation is concentrated on the receiver, to an extent equivalent to the ratio between the surface area of the mirrors and that of the linear receiver.
The solar energy concentrated on the linear receiver is transported using a heat transfer fluid (normally, pressurised water or thermal oil) that circulates throughout the receiver. In this way, the fluid absorbs solar energy, which increases its temperature and, in turn, refrigerates the receiver. The thermal energy is transported by the fluid towards the point of consumption.
At present, there is ample experience in the use of this type of solar power systems in industrial process heat applications. Testimony to that are projects which are currently in operation or under construction; to mention some of the most significant: the 750-kW solar cooling system at the Doha football stadium (Qatar) and the 175-kW facility used to condition the School of Engineering of the University of Seville (Spain). Moreover, albeit to a lesser extent, this type of systems has been used to generate electrical energy in large-size plants. One example within the Spanish territory is the 1.4-MW Puerto Errado plant (Murcia), although there are other large projects around the world, such as the 5-MW Kimberlina plant in California (USA).
Despite the existence of commercial projects in operation and the considerable interest in the market, this technology is still not as competitive as those based on fossil fuels, for which reason it is necessary to insist on the development of actions designed to reduce the cost of the energy produced.
Unfortunately, this type of systems presents certain technological barriers that limit their competitiveness and which are delaying their large-scale implementation. The technological barriers are the following:                High cost of the components: Most manufacturers of solar power industry components are located in Europe and China, whereas solar projects are located at different sites throughout the world (generally places with high solar radiation). Due to the long distances between the production sites and the sites where the projects are finally implemented, in most cases the most economical alternative is to move the manufacturing to the project site. This not only involves the direct cost of building a production plant and the necessary infrastructures to provide services for the workers, but also the search for new suppliers, training new workers or transferring already existing workers, etc. All of this entails a significant increase in the cost of the final product, which makes small-scale projects that cannot recover the cost of transferring the production unfeasible.        Deterioration of the quality of the final product: When the production is transferred to the project site, temporary production plants are built which must be disassembled once the project is completed. This makes it economically unviable to have the machinery and the instrumentation that would be available at a permanent production plant. Consequently, it is necessary to relax the quality requirements as compared to those imposed when the production is performed at a plant with all the resources available.        Long assembly time: Concentrating solar power systems are made up of a large number of elements, which are manufactured separately and assembled at the project location. This process requires highly qualified personnel and the duration is considerable, which not only entails significant assembly expenses (due to the wages of the personnel involved), but, moreover, during the assembly time the plant is still not operative and, therefore, not in production.        Very exacting start-up of the facilities: Due to the nature of concentring solar power systems, which require high precision, it is necessary to check the systems once they have been built in order to ensure the good operation thereof. The inevitable lack of precision of field assembly makes it impossible to meet the necessary precision requirements for solar pointing and tracking, such that it is necessary to perform fine-tuning tasks once the construction has been completed. This type of tasks require workers with specific training, as well as using especially designed instrumentation. All this increases the cost and delays the start-up of this type of plants, thereby considerably increasing the cost of the energy produced.        Limited re-use of the components: Due to the high cost of assembly and the fact that a large part of the facilities are not re-usable (for example, the foundations), this type of projects require long life cycles, since short periods of use would not allow far recovery of the costs generated. Consequently, only long-term projects are viable. However, in the case of a technology such as this one, which is still not too widespread, promoting long-term projects creates uncertainty and unwillingness amongst potential clients, which opt for more conventional technologies for long-term projects. Moreover, this restricts business models wherein only the energy produced is sold to the clients and the property of the system remains in the hands of the promoter, since it requires ensuring a very long-term customer loyalty.

Linear fresnel solar power system that can be transported in a goods container


A method for fabricating a cornea includes affixing a frame to at least one cell culture insert comprising a generally cylindrical structure having a proximal end and a distal end, a base disposed at the proximal end, and a porous membrane disposed between the proximal end and the distal end; affixing a dome-shaped member to the porous membrane within the frame, the dome-shaped member comprising a crown, a dome base, and a surface connecting the crown and the dome base; depositing a material comprising a matrix-forming compound on the frame such that the crown and at least a portion of the surface of the dome-shaped member is coated with the material comprising the matrix-forming compound; and removing the dome-shaped member to produce a fabricated cornea attached to the frame. A system for fabricating a cornea and a cornea scaffold are also described herein.

The cornea is the clear, curved tissue at the front of the eye that protects the eye interior while allowing light to pass through from the exterior of the eye to the visual processing structures and systems inside the eye and nervous system. Corneal replacement therapy is used to restore vision to a person with a damaged cornea from conditions including keratoconus, Fuchs' dystrophy, thinning cornea, cornea scarring, clouding of the cornea, swelling of the cornea, corneal ulcers, and complications caused by eye surgery. In addition to corneal replacement therapy, a supply of corneas is also needed to conduct research to address these and other conditions. Currently, corneal replacement and associated scientific research require tissue donation from a cadaverous donor. A need therefore exists for artificial techniques to efficiently fabricate corneas for corneal replacement therapy and as a supply of samples for corneal research.

System and method for fabricating a cornea


A steel cutting system has a cutting torch on a first side of a slab of steel. A pair of oxygen jets is placed on a second side of the slab of steel.

In most steel making processes, steel slabs exiting a continuous caster must be cut to precise dimensions before they can be processed further. This cutting is usually accomplished with an oxycutting torch. Unfortunately molten metal at the exit of the cut or kerf cools and forms burrs or anomalies on the surface of the slab near the cut. Generally these burrs must be removed before further processing. Commonly, the burrs are removed manually by chiseling or with torches. One solution has been to use a single oxygen jet at the exit point that points along the cut line. This keeps the molten metal hot and is intended to allow the molten metal to fall off by gravity. While this system does seem to reduce the size of the burrs it does not eliminate them.
Thus there exists a need for a system and method that automatically eliminates burrs and anomalies created in cutting a slab of steel.


A geographic area mapping system may enable collecting, from a set of mobile devices, radio frequency data, the radio frequency data comprising information about a set of network connections in the geographic area; collecting lidar data for the geographic area; generating a mapping between the collected radio frequency data and the collected lidar data for the geographic area; and providing a visualization of the mapped radio frequency data and lidar data for the geographic area.

The collection of data about environments and geographic areas is becoming increasingly important as people and organizations try to understand the physical and technological entities in those environments and geographic areas. Determining useful information about environments and geographic areas can be incredibly difficult given the increasing amount of data and data sources about these environments and geographic areas.

Mapping geographic areas using lidar and network data


The invention provides water-swellable polymer compositions having reduced dusting tendencies, i.e, reduced amounts of unassoiated dust having a maximum diameter less than or equal to 10 microns and/or the tendency to generate reduced amounts of unassociatcd dust having a maximum diameter less than or equal to 10 microns upon attrition, and a process for preparing such compositions.

The subject invention pertains to an absorbent polymer having reduced levels of unassociated dust, to an attrition-resistant absorbent polymer and to a process for the preparation of such polymers, and to a process for determining the amount of unassociated matter having a diameter less than or equal to a predetermined size.
In the gel polymerization of water-swellable polymers, monomers are polymerized in aqueous solution. Certain additives, such as crosslinking agents, may be incorporated into the monomer mixture. The product of the polymerization process is typically dried and subjected to mechanical means of particle size reduction and classification including chopping, grinding, and sieving. During such particle size reduction, ultrafine particles or dust, i.e., particles having a mean diameter less than about 10 microns, are unavoidably created.
Japanese Patent Application 6200745-A discloses a water-swellable resin composition having low levels of dust prepared bytreating the polymer with an aqueous solution of a salt and/or hydroxide of a polyvalent metal, the salt and/or hydroxide of the polyvalent metal being provided in the amount of 0.01 to 10 weight percent, based on the weight of the dried polymer.
European Patent Application 103,058 discloses a water-absorbent material consisting of an intimate mixture of 5 to 95 weight percent particulate hydrogel material and 95 to 5 weight percent filler material, which filler material has been treated with up to 1 weight percent of a surfactant. The disclosed materials are said to have reduced dusting tendencies. The disclosed technology, however, would not lead to decreased dusting or the decreased attrition at the site of the manufacture of the hydrogel or during subsequent transport and handling of the hydrogel.
U.S. Pat. No. 4,080,358 discloses a low dusting, free-flowing composition comprising a mixture of a water-soluble acrylamide polymer primarily of a particle size less than 0.5 mm, from 0.1 to 0.5 weight percent based on the weight of the acrylamide of an antidusting agent, e.g., a propylene oxide adduct of glycerol of an average molecular weight between 500 and 2000, and from 1 to 80 weight percent of a highly silicious free-flow aid of submicron to 10 micron particle size.
U.S. Pat. No. 4,734,478 discloses a water-swellable polymer wherein the molecular chains near the surface of the particles are crosslinked. The polymer is prepared by mixing 100 parts water-swellable powder with from 0.001 to 10 parts polyhydric alcohol, and heating the mixture to 90.degree. C. or more to react them. The surface crosslinked particles are said to have no decrease in flowability.
Industry would find great advantage in an aqueous fluid absorbent material which does not dust, e.g., which comprises no more than 2.5 ppm unassociated particles less than 10 microns in diameter. Industry would further find advantage in an attrition-resistant aqueous fluid absorbent material, e.g., which comprises no more than 35 ppm unassociated dust upon roll-milling for 20 minutes, and/or which comprises no more than 15 ppm unassociated dust upon roll-milling for 10 minutes. Industrywould further find advantage in a process for reducing the level of particles less than 10 microns in diameter in a given composition by at least 90 percent. Industry would further find advantage in a process for ascertaining the amount of unassociated dust in a water-swellable polymer composition.

Absorbent polymer having reduced dusting tendencies


Disclosed herein is compound 1

1. Field of the Invention
This disclosure relates to pharmaceutical compositions and medical treatments. In particular, this disclosure relates to the use of prostaglandin D2 antagonists in said compositions and treatments.
2. Description of the Related Art
The potential of prostaglandin D2 antagonists in the treatment of allergy-related conditions is well documented and supported in the open literature, for example, Matsuoka and colleagues reported that "PGD2 functions as a mediator of allergic asthma . . . it may also play an important role in other allergic disorders such as allergic rhinitis and atopic dermatitis. The DP receptor may thus represent a new therapeutic target for the treatment of such allergic reactions." (Science, vol 298, 17 Mar. 2000) Similar disclosures are found in Tsuri (J. Med. Chem., 40 (22), 3504–3507, 1997), Hirai (J. Exp. Med., 193, Number 2, Jan. 15, 2001 255–261), and several patent documents, including U.S. patent publication 20030055077 and U.S. Pat. No. 6,083,974, which teach the use of prostaglandin D2 antagonists for the treatment of certain allergic conditions.
The relationship between prostaglandin D2 and systemic mastocytosis is also known. Negishi teaches "Systemic mastocytosis is a disease in which the mast cell population increases in various tissues and produces PGD2. Prominent symptoms are vasodilation manifested by flushing, tachycardia and occasionally hypotension and clyspnea, and increased intestinal motility resulting in abdominal cramping, diarrhea, nausea and vomiting." (Prog. Lip. Res., vol 32, no. 4, pp 417–434, 1993)
U.S. Pat. No. 6,083,974 teaches the use of PGD2 antagonists "as drugs for treating diseases in which mast cell dysfunction is involved, for example, systemic mastocytosis and disorder of systemic mast cell activation as well as for tracheal contraction, asthma, allergic rhinitis, allergic conjunctivitis, urticaria, ischemic reperfusion injury, inflammation, and atopic dermatitis."
Wright teaches that prostaglandin D2 regulates mucous secretion, and has "both contractile and a relaxant role . . . in the gastrointestinal tract", and that "the DP receptor may mediate mucous secretion and cytoprotection". (European Journal of Pharmacology 377 (1999) 101–115)
In addition to the aforementioned conditions, U.S. Pat. No. 6,410,583 teaches the use of prostaglandin D2 antagonists for the treatment of pulmonary congestion.
Additionally U.S. Patent Publication 20030158246 discloses prostaglandin D2 antagonists which "are useful to treat, prevent, or ameliorate in mammals and especially in humans: respiratory conditions, allergic conditions, pain, inflammatory conditions, mucus secretion disorders, bone disorders, sleep disorders, fertility disorders, blood coagulation disorders, trouble of the vision as well as immune and autoimmune diseases. In addition, such a compound may inhibit cellular neoplastic transformations and metastic tumor growth and hence can be used in the treatment of cancer." Additionally, the '246 publication discloses that the prostaglandin D2 antagonists "may also be of use in the treatment and/or prevention of prostaglandin D2 mediated proliferation disorders such as may occur in diabetic retinopathy and tumor angiogenesis." The '246 publication also teaches the use of prostaglandin D2 antagonists for the treatment and/or prevention of "allergic rhinitis, nasal congestion, rhinorrhea, perennial rhinitis, nasal inflammation, asthma including allergic asthma, chronic obstructive pulmonary diseases and other forms of lung inflammation; pulmonary hypotension; sleep disorders and sleep-wake cycle disorders; prostanoid-induced smooth muscle contraction associated with dysmenorrhea and premature labor; eosinophil-related disorders; thrombosis; glaucoma and vision disorders; occlusive vascular diseases, such as for example atherosclerosis; congestive heart failure; diseases or conditions requiring a treatment of anti-coagulation such as post-injury or post surgery treatment; rheumatoid arthritis and other inflammatory diseases; gangrene; Raynaud's disease; mucus secretion disorders including cytoprotection; pain and migraine; diseases requiring control of bone formation and resorption such as for example osteoporosis; shock; thermal regulation including fever; rejection in organ transplant and by-pass surgery, and immune disorders or conditions in which immunoregulation is desirable. More particularly the disease to be treated is one mediated by prostaglandin D2 such as nasal congestion, allergic rhinitis, pulmonary congestion, and asthma including allergic asthma."
In citing the foregoing references, and other references cited herein, applications make no admission as to whether any of said references constitutes prior art. Rather, the determination of what constitutes prior art is a legal decision made on the basis of the dates said references were made available to the public, the authors or inventors of said references, and the effective filing date of the disclosure made herein.

This patent is subject to a terminal disclaimer.

Abstract: Disclosed herein is compound 1

Abstract: or a pharmaceutically acceptable salt, or a prodrug thereof. Compound 1 is useful for treating or preventing a variety of diseases or conditions. Results presented herein also demonstrate that Compound 1 is a prostaglandin D2 antagonist, and as such is useful in the treatment or prevention of prostaglandin D2 mediated conditions or diseases.

Abstract: A method comprising administering a prostaglandin D2 antagonist to a mammal suffering from a disease or condition selected from the group consisting of the gastrointestinal tract disorders or diseases, hyperalgesia, allodynia, abdominal cramping, glaucoma, ocular hypertension, and ocular hypotension is also disclosed herein.

Abstract: Pharmaceutical compositions and products comprising compound 1 are also disclosed.


The present invention relates to a method for applying a principle of Deterministic Lateral Displacement (DLD), and for separating cells depending on the particle sizes on the basis of the DLD principle after capturing targeted cells or untargeted cells on a carrier and thereby increasing particle sizes.

Separation of specific cells from a humoral mixed sample (e.g. blood or culture medium) is a technique required for basic study, diagnosis and treatment. Generally, the technique is known to be useful for separating cells having specific densities (specific gravity) (e.g. white blood cells and red blood cells) by centrifugation or the like. Other than that, methods such as a flow cytometry method and a magnetic separation method have been proved to be useful for this purpose, and as described in Patent Literature 1, a method for separating cells from a humoral mixed sample depending on their sizes by a filter structure is also known. Furthermore, as described in Patent Literature 2, a method for separating cells depending on their sizes by the use of a fluid device using a principle referred to as Deterministic Lateral Displacement (DLD) is also known.
However, in the separation methods described in Patent Literatures 1 and 2, it is difficult to separate the cells the kinds of which are different but whose sizes are similar to each other, since the methods are intended to separate cells from the humoral mixed sample depending on sizes of the cells themselves. In addition, in the separation method described in Patent Literature 3, a separation method in which cells are formed as a composite particle and then a sieve membrane is utilized is used, but in a case where such a separation method is used, there are problems that the processing has troubles such as an accompanying washing step, loss of cells, or the like, and thus a rapid, convenient and highly accurate separation and purification method is required. In addition to this, methods such as in Patent Literatures 4 to 6 have been proposed.
Furthermore, there has been also attempted the separation of cells in blood depending on their sizes or the like. However, the separation of circulating tumor cells (CTC) in blood has been difficult by a method based on the aforementioned DLD principle, because its size was similar to each size of white blood cells (10 to 20 μm).
Moreover, in the separation methods described in Patent Literatures 1 and 2, clogging is generated at a basic principle portion for separation due to the influence of minute aggregates existing in the sample, and thus there are some cases where the accuracy of separation is lowered or separation is made impossible.
Minute aggregates can be produced by aggregation of fibrin, other denatured proteins, fats and the like. In addition, each of the minute aggregates has a size ranging from a size equal to each blood cell such as leucocyte to a size larger than 200 μm, and is characteristically viscous. These minute aggregates are also present in fresh samples immediately after sampling, and a trend is that the longer the storage period is and the lower the storage temperature is, the larger the number and each size of the minute aggregates become. Furthermore, the minute aggregates are characteristically present even in a sample obtained by mixing with an anticoagulant and the like during sampling.
Accordingly, in a case where a known cell-separating treatment is executed without removing these minute aggregates, clogging may be generated on a part of the device due to the minute aggregates, resulting in lowering accuracy of the separation of the targeted cell and making processing itself difficult.
In contrast, minute aggregate-removing methods using a minute aggregate-removing filter as disclosed in Patent Literatures 7 and 8 are disclosed. However, although a large amount of samples can be treated in these methods, the targeted cells are lost, and thus the methods are unsuitable for separating rare cells in the sample without loss. Furthermore, in a filtration removal method using a commercially available nylon mesh filter, there is a case where the targeted cells can be lost, and minute aggregates cannot be completely removed.

Method for separating cells, and device therefor


In case of epitaxially growing a single crystal silicon layer by catalytic CVD on a material layer in lattice alignment with single crystal silicon, i.e. a substrate of single crystal silicon, sapphire, spinel, or the like, the total pressure of the growth atmosphere is maintained in the range from 1.33xc3x9710xe2x88x923 Pa to 4 Pa at least in the initial period of the epitaxial growth, or alternatively, partial pressure of oxygen and moisture in the growth atmosphere is maintained in the range from 6.65xc3x9710xe2x88x9210 to 2xc3x9710xe2x88x926 Pa at least in the initial period of the epitaxial growth. Thus, the maximum oxygen concentration of the epitaxially grown single crystal silicon layer becomes not higher than 3xc3x971018 atoms/cmxe2x88x923 at least in a portion with the thickness of 10 nm from the boundary with the substrate 4. It is thus ensured to epitaxially grow a high-quality single crystal silicon layer at a lower temperature than that of existing CVD.

The present application claims priority to Japanese Application No. P11-352349 filed Dec. 10, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
This invention relates to a single-crystal silicon layer, its epitaxial growth method and semiconductor, which are suitable for use in thin-film transistors (TFT), for example.
2. Description of the Related Art
Heretofore, a typical method for epitaxially growing a single crystal silicon (Si) layer is to decompose and grow silane (SiH4), dichlorosilane (Si2Cl2H4), trichlorosilane (SiCl3H4), silicon tetrachloride (SiCl4), or the like, under the temperature of about 700 through 1200xc2x0 C., hydrogen atmosphere, pressure of 1.33xc3x97104 to 1xc3x97105 Pa (100 to 760 Torr) by using chemical vapor deposition (CVD).
However, the method of epitaxially growing a single crystal silicon layer by conventional CVD mentioned above involves the problem that the growth temperature is high. More specifically, in CVD, since energy required for chemical interaction and growth during epitaxial growth of a single crystal silicon layer is all supplied in form of heat energy obtained by heating a substrate to a high temperature, decreasing the growth temperature to or below 700xc2x0 C. will invite a crystallographic deterioration and a decrease of the growth rate. Therefore, it is not possible to decrease the growth temperature from about 700xc2x0 C. Further, when the growth temperature is in the range of about 1000 to 1200xc2x0 C., the ratio of decomposed reactant gas (silane, dichlorosilane, or the like) contributing to epitaxial growth of a single crystal silicon layer is around 1 to 5%. When the growth temperature is 800xc2x0 C., it further decreases to around 0.1 to 0.5%. Thus the efficiency of use of reactive gas is seriously low, and it invites an increase of its cost. Furthermore, since exhaust reactant gas (silane, dichlorosilane, and so forth) are harmful, a process for change it harmless, such as burning or absorption, is required to prevent the reactant gas from being released in the air. Therefore, when the efficiency of the use of the reactant gas seriously decreases as indicated above, the expense for the process for changing it harmless also increases.
It is therefore an object of the invention to provide a epitaxial growth method of a single crystal silicon layer capable of epitaxially growing a high-quality single crystal silicon layer at a temperature lower than that of conventional CVD; a single crystal silicon layer obtained by the method; and a semiconductor device using such a single crystal silicon layer.
The Inventor made researches toward solution of the above problems involved in conventional techniques. These researches are outlined below.
Recently, as a growth method of polycrystalline silicon layers and amorphous silicon layers, a growth method called catalytic CVD are being remarked (for example, Japanese Patent Laid-Open Publication No. hei 10-83988 and Applied Physics, Vol. 66, No. 10, p. 1094(1997)). This catalytic CVD uses catalytic cracking reaction between a heated catalyst and reactant gas (source material gas).
The Inventor made consideration about application of catalytic CVD to epitaxial growth of a single crystal silicon layer. That is, catalytic CVD, in its first stage, brings reactant gas (such as silane and hydrogen in case of using silane as the source material of silicon) into contact with a hot catalyst heated to 1600 through 1800xc2x0 C., for example, to activate the reactant gas and thereby make silicon atoms, or clusters of silicon atoms, and hydrogen atoms, or clusters of hydrogen atoms, having high energies, and in its second stage, raises the temperature of these silicon atoms and hydrogen atoms or molecules having high energies, or a substrate that supplies their clusters, to a high temperature, thereby to supply and support the energy required particularly for silicon atoms to align along the crystalline orientation of the substrate. Therefore, catalytic CVD enables epitaxial growth of a single crystal silicon layer even at a lower temperature than that of conventional CVD, such as around 350xc2x0 C., for example.
However, according to results of various experiments made by the Inventor, in the case where a single crystal silicon layer is epitaxially grown at a low temperature by existing catalytic CVD, oxygen is more liable to be brought into the growth layer than that epitaxially grown by conventional CVD, and the oxygen concentration in the single crystal silicon layer obtained often exceeds several atomic % (at %). This amounts at least to 5xc3x971020 atoms/cm3 (atoms/cc) when converted into atomic concentration. Since the maximum solution of oxygen in silicon is 2.5xc3x971018 atoms/cc (for example, Semiconductor Handbook 2nd Edition, pp.128-129, edited by Hisayoshi Yanai, Ohmusha, 1977), and the said oxygen concentration is far beyond the maximum solution of oxygen in silicon, 2.5xc3x971018 atoms/cc. When oxygen over the maximum solution is contained in silicon, oxygen precipitates forming silicon oxide, and sometimes results in forming an oxide thin film around silicon crystal grains or sometimes results in forming oxide grains with a further increase of oxygen.
Under the circumstances, the Inventor made researches about growth conditions for epitaxial growth of a single crystal silicon layer by catalytic CVD toward obtaining a high-quality single crystal silicon layer.
That is, repeated were experiments of epitaxially growing single crystal silicon layers by using catalytic CVD and variously changing process conditions under a low temperature range (200 through 600xc2x0 C.) and then evaluating them. As a result, it was found that, for growing high-quality single crystal silicon layers by catalytic CVD, conditions such as pressure of the vapor-phase growth atmosphere, partial pressure of oxygen and moisture in the growth atmosphere, and soon, were absolutely different from those of conventional CVD. More specifically, at least in the initial period of growth, the total pressure of the growth atmosphere was set to a much lower pressure than that of existing catalytic CVD, e.g., in the range from 1.33xc3x9710xe2x88x923 Pa to 4 Pa (from 0.01 mTorr to 30 mTorr), it was confirmed that the maximum oxygen concentration at least near the boundary with the substrate was as very low as 3xc3x971018 atoms/cc (0.006 at %), and high-quality single crystal silicon layers could be grown. Also when the partial pressure of oxygen and moisture in the growth atmosphere at least in the initial period of growth was set in the range from 6.65xc3x9710xe2x88x9210 Pa to 2xc3x9710xe2x88x926 (from 0.005xc3x9710xe2x88x926 mTorr to 15xc3x9710xe2x88x926 mTorr), it was confirmed that the oxygen concentration at least near the boundary with the substrate was similarly as very low as 3xc3x9710 atoms/cc (0.006 at %), and high-quality single crystal silicon layers could be grown. This partial pressure of oxygen and moisture can be obtained when oxygen and moisture around 0.5 ppm in total are contained in the reactant gas.
The present invention has been made through studies based on the above knowledge of the Inventor.
According to the first aspect of the invention, there is provided a single crystal silicon layer epitaxially grown by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
the maximum oxygen concentration thereof being 3xc3x971018 atoms/cm3 at least in a region having the thickness of 10 nm thick from the boundary between the material layer and the single crystal silicon layer.
In the first aspect of the invention, the maximum oxygen concentration at least in a region with the thickness of 10 nm from the boundary between the material layer in lattice alignment with single crystal silicon and the single crystal silicon layer is preferably not higher than 2xc3x971018 atoms/cm3. Further, the maximum oxygen concentration at least in a region with the thickness of 50 nm, or 100 nm, from the boundary between the material layer in lattice alignment with single crystal silicon and the single crystal silicon layer is preferably not higher than 2xc3x971018 atoms/cm3.
According to the second aspect of the invention, there is provided a single crystal silicon layer having a thickness not exceeding 1 xcexcm epitaxially grown by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
the maximum oxygen concentration thereof being 3xc3x971018 atoms/cm3.
In the second aspect of the invention, thickness of the single crystal silicon layer may be not larger than 100 nm, or not larger than 50 nm. Additionally, the maximum oxygen concentration is preferably not higher than 2xc3x971818 atoms/cm3.
According to the third aspect of the invention, there is provided a single crystal silicon layer epitaxially grown by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
being epitaxially grown by maintaining the total pressure of the growth atmosphere in the range from 1.33xc3x9710xe2x88x923 Pa to 4 Pa at least in an initial period of the epitaxial growth. According to the fourth aspect of the invention, there is provided a single crystal silicon layer epitaxially grown by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
being epitaxially grown by maintaining the partial pressure of oxygen and moisture in the growth atmosphere in the range from 6.65xc3x9710xe2x88x9210 Pa to 2xc3x9710xe2x88x926 Pa at least in an initial period of the epitaxial growth.
According to the fifth aspect of the invention, there is provided an epitaxial growth method for epitaxially growing a single crystal silicon layer by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
the total pressure of the growth atmosphere being maintained in the range from 1.33xc3x9710xe2x88x923 Pa to 4 Pa at least in an initial period of the epitaxial growth.
According to the sixth aspect of the invention, there is provided an epitaxial growth method for epitaxially growing a single crystal silicon layer by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
the partial pressure of oxygen and moisture in the growth atmosphere being maintained in the range from 6.65xc3x9710xe2x88x9210 Pa to 2xc3x9710xe2x88x926 Pa at least in an initial period of the epitaxial growth.
According to the seventh aspect of the invention, there is provided a semiconductor device having a single crystal silicon layer which is epitaxially grown by catalytic CVD on a material layer in lattice alignment with single crystal silicon, characterized in:
the single crystal silicon layer having the maximum oxygen concentration of 3xc3x971018 atoms/cm3 at least in a region thereof to be used as a carrier channel.
In the seventh aspect of the invention, the maximum oxygen concentration of the single crystal silicon layer is preferably not higher than 2xc3x971018 atoms/cm3.
The semiconductor device may be basically any that uses the single crystal silicon layer. Specifically, it may be a thin-film transistor (TFT), which is MISFET, or junction FET, bipolar transistor, or the like, for example. Thickness of the carrier channel region in TFT is typically around 10 through 100 nm. Furthermore, not limited to these transistors, the semiconductor device may be a diode, capacitor or resistor, as well.
In the present invention, growth temperature of the single crystal silicon film by catalytic CVD is, for example, 200 through 600xc2x0 C.
In the present invention, the base layer for epitaxially growing the single crystal silicon layer on, i.e. the material layer in lattice alignment with single crystal silicon, may be made of single crystal silicon, or sapphire, spinel, or the like. The xe2x80x9csingle crystal siliconxe2x80x9d is used to involve those including sub-boundaries.
According to the first aspect of the invention having the above-summarized structure, since the maximum oxygen concentration is not higher than 3xc3x971018 atoms/cm3, which is much lower than that of a single crystal silicon layer grown at a low temperature by existing catalytic CVD at least in a region with the thickness of 10 nm from the boundary between the material layer in lattice alignment with single crystal silicon and the single crystal silicon layer, a high-quality single crystal silicon layer can be obtained.
According to the second aspect of the invention having the above-summarized structure, since the maximum oxygen concentration is not higher than 5xc3x971018 atoms/cm3, which is much lower than that of a single crystal silicon layer grown at a low temperature by existing catalytic CVD, a high-quality single crystal silicon layer can be obtained.
According to the third and fifth aspects of the invention having the above-summarized structures, since the total pressure of the growth atmosphere is set in the range from 1.33xc3x9710xe2x88x923 Pa to 4 Pa at least in the initial period of epitaxial growth, partial pressure of oxygen and moisture in the growth atmosphere can be maintained in the range from 6.65xc3x9710xe2x88x9210 Pa to 2xc3x9710xe2x88x926 Pa at least in the initial period of epitaxial growth, and the amount of oxygen brought into the growth layer can be diminished significantly. As a result, the maximum oxygen concentration is not higher than 3xc3x971018 atoms/cm3, which is much lower than that of a single crystal silicon layer grown at a low temperature by existing catalytic CVD at least in a region with the thickness of 10 nm from the boundary between the material layer in lattice alignment with single crystal silicon and the single crystal silicon layer, and therefore, a high-quality single crystal silicon layer can be obtained.
According to the fourth and sixth aspects of the invention having the above-summarized structures, since the partial pressure of oxygen and moisture in the growth atmosphere is set in the range from 6.65xc3x9710xe2x88x9210 Pa to 2xc3x9710xe2x88x926 Pa at least in the initial period of epitaxial growth, the amount of oxygen brought into the growth layer can be diminished significantly. As a result, the maximum oxygen concentration is not higher than 3xc3x971018 atoms/cm3, which is much lower than that of a single crystal silicon layer grown at a low temperature by existing catalytic CVD at least in a region with the thickness of 10 nm from the boundary between the material layer in lattice alignment with single crystal silicon and the single crystal silicon layer, and therefore, a high-quality single crystal silicon layer can be obtained.
According to the seventh aspect of the invention having the above-summarized structure, since the maximum oxygen concentration is not higher than 3xc3x971018 atoms/cm3, which is much lower than that of a single crystal silicon layer grown at a low temperature by existing catalytic CVD at least in a region to be used as the carrier channel, the single crystal silicon layer has a high quality, and it is possible to obtain a high-performance semiconductor device like TFT having a high carrier mobility, by using this single crystal silicon layer.
The above, and other, objects, features and advantage of the present invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings.

Single crystal silicon layer, its epitaxial growth method and semiconductor device


An object of the present invention is to provide a polymer electrolyte composition ensuring high durability even under high-temperature low-humidification conditions (for example, an operation temperature of 100° C. with 50° C. humidification (corresponding to a humidity of 12 RH %)), and a proton exchange membrane comprising the polymer electrolyte composition. The present invention provides a polymer electrolyte composition comprising (A) a polymer compound having an ion exchange group, (B) a polyphenylene sulfide resin, and at least one resin selected from (C) a polyphenylene ether resin and (D) a polysulfone resin, and a proton exchange membrane comprising the above polymer electrolyte composition.

A fuel cell is a cell in which hydrogen, methanol or the like is electrochemically oxidized and thereby the chemical energy of fuel is directly converted into an electric energy and taken out, and this is attracting attention as a clean electric energy supply source. In particular, a solid polymer electrolyte fuel cell works at a low temperature as compared with others and is expected to be an automobile alternative power source, a domestic cogeneration system, a portable generator or the like.
The solid polymer electrolyte fuel cell comprises at least a membrane electrode assembly in which a gas diffusion electrode obtained by stacking an electrode catalyst layer and a gas diffusion layer is joined on each of both surfaces of a proton exchange membrane. The proton exchange membrane as used herein means a material having a strongly acidic group such as sulfonic acid group and carboxylic acid group in the polymer chain and having a property of selectively passing a proton. The proton exchange membrane which is suitably used is a perfluoro-based proton exchange membrane as represented by Nafion (registered trademark, produced by du Pont) having high chemical stability.
During the operation of a fuel cell, a fuel (e.g., hydrogen) is supplied to the gas diffusion electrode on the anode side, an oxidizing agent (e.g., oxygen, air) is supplied to the gas diffusion electrode on the cathode side, and both electrodes are connected through an external circuit, thereby actuating the fuel cell. More specifically, when the fuel is hydrogen, the hydrogen is oxidized on an anode catalyst to produce a proton, and this proton passes through a proton conductive polymer in the anode catalyst layer, then moves in the proton exchange membrane and passes through a proton conductive polymer in the cathode catalyst layer to reach on the cathode catalyst. On the other hand, an electron produced simultaneously with the proton by the oxidation of hydrogen passes through the external circuit to reach the gas diffusion electrode on the cathode side and reacts with the proton and oxygen in the oxidizing agent to produce water, and an electric energy can be taken out at this time.
In this case, the proton exchange membrane must act also as a gas barrier and if the gas permeability of the proton exchange membrane is high, the hydrogen on the anode side leaks toward the cathode side and the oxygen on the cathode side leaks toward the anode side, that is, a cross leakage is generated, as a result, a so-called chemical short state is produced and a good voltage cannot be taken out.
The solid polymer electrolyte fuel cell is usually operated at around 80° C. in order to bring out high output properties, but in usage for automobiles, assuming travel of an automobile in the summer season, the fuel cell is required to be operable even under high-temperature low-humidification conditions (an operation temperature in the vicinity of 100° C. with 50° C. humidification (corresponding to a humidity of 12 RH %)). However, when a fuel cell using a conventional perfluoro-based proton exchange membrane is operated for a long time under high-temperature low-humidification conditions, this causes a problem in that pinholes are generated in the proton exchange membrane and cross-leakage is brought about, and sufficiently high durability is not obtained.
With respect to the method for enhancing the durability of the perfluoro-based proton exchange membrane, studies have been reported to enhance the durability by the reinforcement using a fibrillated polytetrafluoroethylene (PTFE) (see, Japanese Unexamined Patent Publication (Kokai) No. 53-149881 and Japanese Examined Patent Publication (Kokoku) No. 63-61337), the reinforcement using a stretched PTFE porous film (see, Kokai No. 8-162132), the reinforcement of adding inorganic particles (see, Kokai Nos. 6-111827 and 9-219206 and U.S. Pat. No. 5,523,181), or the reinforcement using a porous body comprising an aromatic ring-containing resin (see, Kokai Nos. 2001-514431 and 2003-297393). However, in these methods, durability sufficiently high to solve the above-described problems cannot be achieved.

Polymer electrolyte composition containing aromatic hydrocarbon-based resin


Downhole apparatus in the form of a valve (140) comprises a body (148) defining a bore (168) with a curved disc closure member (142) positioned in the bore. First and second retaining members (144, 146) are positioned on respective sides of the disc (142) for retaining the disc in a closed position and to hold pressure from both sides. One of the retaining members (144) is retractable to permit opening of the valve disc (142). The disc (142) may be locked closed by locking the retractable retaining member (144) in position. On release of the member (144), application of fluid pressure to portions of the member (144) will retract the member (144).

This invention relates to apparatus for use in downhole operations. In particular, but not exclusively, the apparatus relates to an isolation valve intended for use in completion testing and in operations which take place immediately following completion testing.
In the oil and gas exploration and extraction industries, deep bores are drilled to gain access to hydrocarbon-bearing strata. The section of bore which intersects this strata or xe2x80x9cproduction zonexe2x80x9d is typically provided with a steel xe2x80x9clinerxe2x80x9d, while the section of bore extending to the surface is lined with steel xe2x80x9ccasingxe2x80x9d. Oil and gas is extracted from the production zone through production tubing extending through the casing from the upper end of the liner. The production tubing is formed of a string of threaded sections or xe2x80x9csubsxe2x80x9d which are fed downwards from the surface, additional subs being added at the surface until the string is of the desired length. As the string is assembled and fed into the bore its pressure integrity, or xe2x80x9ccompletionxe2x80x9d, is tested at regular intervals. Such testing is also carried out on the complete string. The testing is accomplished by pressurising the internal bore of the string. Of course this requires that the string bore is sealed at its lower end.
This sealing of the string bore is generally accomplished using a valve or plug which will normally remain closed or in place once testing is completed, to allow the packers mounted on the string to be set to locate and seal the string within the casing or liner. The valve or plug may then be opened or removed to permit formation fluid to flow upwardly to the surface through the production tubing. The opening or removal operation generally requires running in of an appropriate tool on, for example, wireline or coiled tubing, which will involve additional time and expense.
It is among the objectives of embodiments of this invention to obviate or mitigate these disadvantages. It is a further objective of embodiments of this invention to provide an isolation valve which will hold pressure in two directions, that is from the sump side and the surface side.
According to a first aspect of the present invention there is provided a downhole valve comprising a body defining a bore, a valve closure member positioned in the bore, first and second retaining members positioned on respective sides of the valve closure member for retaining the valve closure member in a closed position and to hold pressure from both sides, one of the retaining members being retractable to permit opening of the valve closure member.
In use, such a downhole valve will hold pressure from both the surface side and the sump side. The terms xe2x80x9cabovexe2x80x9d and xe2x80x9cbelowxe2x80x9d are used herein, but those of skill in the art will of course realise that the invention may be used with equal utility in inclined or horizontal bores, and the orientation of the valve may be varied.
Preferably, with the valve closure member in the open position, the body defines a slick bore.
Preferably also, the valve closure member comprises a flapper in the form of a disc. Most preferably, the disc is in the form of a curved or concave disc. In the preferred embodiment a convex surface of the disc engages a valve seat.
Preferably also, one of the retaining members is extendable to maintain the valve closure member in an open position and to provide a slick bore. In the preferred embodiment one of the retaining members is both retractable, to permit opening of the valve closure member, and extendable to maintain the valve closure member in the open position.
Preferably also, one of the retaining members incorporates a valve seat. The valve seat may include an elastomeric seal located in an end surface of the retaining member. Most preferably, the retaining member incorporating the valve seat is non-retractable. Alternatively, a separate valve seat may be provided.
Preferably also, the retractable retaining member is moveable by application of fluid pressure thereto. The fluid pressure may be provided by well fluid in the borehole, and most preferably by the well fluid in the body bore. The supply of fluid from the body bore to actuate the retaining member may be controlled by an appropriate valve, such as described in PCT/GB95/02046.
Preferably also, the retractable retaining member includes a sleeve portion defining a piston, such that application of fluid pressure between the sleeve portion and the body tends to retract the member from a retaining position. The member may be biassed towards the retaining position by biassing means, such as a spring.
Preferably also, the retractable retaining member is lockable in the retaining position, but is releasable, most preferably on application of actuating fluid pressure. Most preferably, the unlocking of the retractable retaining member is controlled by a ratchet assembly comprising first and second axially relatively movable parts, each part defining a toothed face, and a ratch member located between the toothed faces, pressure induced reciprocal movement of the parts advancing the ratch member axially along the toothed face of the first part, in an advanced position the ratch member engaging a unlocking member such that further movement of the first part actuates the unlocking member to release the retaining member.
Additionally, or alternatively, the retractable retaining member may be releasable by application of physical force by a further tool located in the bore. Preferably, the unlocking member defines a tool engaging profile for cooperating with said further tool.
Preferably also, the retractable retaining member may be latched in the retracted position, to permit opening of the valve closure member, and then released to return to an extended position to maintain the valve closure member open.
Preferably also, the valve closure member is in the form of a flapper and is mounted on a valve carriage which, with the retaining member retracted, is axially movable towards the retaining member such that the retaining member may contact the flapper and push the flapper towards the open position. The valve carriage and the retaining member are preferably connected by a resilient link. In the preferred embodiment, retraction of the retaining member is achieved by pressurising the bore, which also maintains the valve carriage and flapper in the closed position, with the flapper in sealing contact with the other retaining member. Bleeding off bore pressure following retraction of the retaining member allows the flapper to lift from the other retaining member and the valve carriage to follow the retracted retaining member, and the end of the retaining member to contact the flapper and push the flapper to the open position.
The valve may include vent means for equalising pressure across the valve closure member prior to the retractable retaining member permitting opening. The vent means may be openable by initial application of fluid pressure, to permit fluid communication across the valve member. Most preferably, the vent means includes a moveable member, such as a sliding sleeve, which initially closes a vent passage but is moveable to open the passage. Preferably also, the moveable member also serves, in its initial position, to lock the retractable retaining member in the retaining position.
The other of the retaining members may be biassed to move the valve closure member to the open position. Alternatively, the valve closure member may be provided with means for biassing the member towards the open position.
According to another aspect of the present invention there is provided a method of completing a downhole string including the steps of:
providing a valve in a tubular string, which valve is capable of holding pressure from both above and below;
running the string into a bore with the valve closed;
securing the string in the bore; and
opening the valve to permit flow of fluid through the string.
Conventionally, in a completion operation, the string is provided with a normally-closed valve which opens in response to higher pressure in the well to permit well fluid to flow into the string. Thus, such valves are not suitable for use as safety valves, and separate safety valves must be provided in the string to safeguard against surges of fluid up through the string when upper end of the string is opened. A valve which will hold pressure from both the sump and surface sides allows for completion testing against the valve and may also serve as a safety valve. In the method of this aspect of the invention top filling may be utilised for filling the string with fluid as it is run into the bore.
According to a further aspect of the present invention there is provided a downhole valve comprising: a curved valve closure member defining a convex face and a seal area on said face; and a valve seat for engaging the seal area.
Preferably, the valve includes a tubular valve body having a main axis and the seal area defines a surface which is substantially perpendicular to said axis.
According to a still further aspect of the present invention there is provided a downhole valve for holding fluid pressure in a first direction, the valve including a non-planar valve closure member defining a peripheral seal surface and a valve seat having a corresponding sealing area, the seal surface and sealing area being substantially perpendicular to said first direction.
It has been found that the sealing capabilities of valves in accordance with this aspect of the invention compare favourably in comparison with valves in which the seal surface simply coincides with the surface of the valve closure member.
Preferably, the valve closure member is a curved flapper, and most preferably the seal surface is provided at the periphery of the convex face of the member.
Preferably also, the sealing area includes a resilient sealing portion.
According to a yet further aspect of the present invention there is provided a ratchet arrangement for downhole apparatus, the arrangement comprising first and second parts, each part defining a toothed face, and a ratch member located between the toothed faces, the parts being axially relatively movable by application of fluid pressure thereto, wherein reciprocal movement of the parts advances the ratch member axially along the toothed faces.
The ratch member may engage a part of another tool or device on reaching an advanced position, and serve to actuate the tool or device or transfer force thereto from one of the parts. In a preferred embodiment the ratch member is utilised to transfer force from the first part to unlock a further part of a valve to permit opening of the valve.
Preferably, the first part defines a piston and is movable on application of fluid pressure thereto, and the first part has a stroke corresponding to the tooth spacing on the toothed faces of the parts such that each pressure cycle will advance the ratch member one tooth. Accordingly, by providing a known number of teeth and knowing the initial position of the ratch member, the ratch member may be moved to a predetermined advanced position by application of a predetermined number of pressure cycles. This feature is useful when used in conjunction with pressure actuated tools for use in completion operations, where pressure is used in, for example, completion testing and setting packers. Using this aspect of the invention, the operation of a particular pressure actuated tool, such as an isolation valve, may be controlled by the ratchet assembly, and will only commence after a predetermined number of pressure cycles, thus accommodating completion testing operations and the setting of packers.
The piston and toothed face of the first part may be integral. Alternatively, the toothed face may form part of a unit, incorporating the other toothed face and the ratch member, which is separable from the tool or device provided in combination with the ratchet assembly.
Preferably, the ratch member comprises first and second portions and a spring portion acting therebetween to urge the first and second portions into engagement with the respective toothed faces. Preferably, the ratch member portions are combined as a single integral part.

Downhole apparatus for controlling fluid pressure


A blade of an turbomachine having an airfoil with a leading edge and a root; a base attached to the root of the airfoil; a dovetail portion of the base engageable with disk; a slot in the base generally parallel to a face of the base extending between opposite sides of the base, and a vibration adsorbing insert snuggly fitted into the slot.

The invention relates to blades for turbo machines and, in particular, to leading edge treatments to increase blade tolerance to erosion.
Water is sprayed in a compressor to wash the blades and improve performance of the compressor. Water washes are used to clean the compressor flow path especially in large industrial gas turbines, such as those used by utilities to generate electricity. Water is sprayed directly into the inlet to the compressor uniformly across the flow path. The rotating first stage blades of the compressor tend to erode at their leading edges of the airfoil especially at the root of the airfoil, which is where the blade airfoil attaches to the blade platform.
Water spray is a source of erosion to the leading edges of compressor blades and especially to first stage compressor blades. Other sources of erosion include debris and moisture in the intake air that erode the leading edge of a compressor blade and combustion products that erode the trailing edge of a turbine blade (also known as a bucket). Erosion can pit, crevice or otherwise deform the edge surfaces of a compressor blade and turbine bucket. As erosion continues, the population of pits and crevices increases and they deepen into the airfoil surface of the blade.
In addition, a blade is under tremendous stress due to centrifugal forces and forced vibration due to the airflow and the turbo machine. These stresses tear at the erosion pits and crevices and potentially lead to a high cycle fatigue (HCF) crack in the blade. Once a crack develops, the high steady state stresses due to the centrifugal forces that act on a blade and the normal vibratory stresses on the blade can cause the crack to propagate through the blade and eventually cause the blade to fail.

Compressor blade with dovetail slotted to reduce stress on the airfoil leading edge


The present invention provides a catalyst system that exhibits unprecedented catalyst efficiencies and control of desired properties in the polymer product. The catalyst system includes a new generation titanium catalyst in combination with an electron donor described by the formula: ##STR1## wherein R.sub.1 is an alkyl or cycloalkyl group containing a primary or secondary carbon atom attached to the silicon atom; R.sub.2 and R.sub.3 are alkyl or aryl groups; and R.sub.4 is an alkyl or cycloalkyl group with a primary or secondary carbon atom attached to the silicon atom. The system has a catalyst efficiency of over 30 kg/g-cat.h as the Si/Ti mole ratio varies from 4-20 in the system. The system easily achieves efficiencies over 30 kg/g-cat.h. The system also exhibits good control over the xylene solubles of the polymer products.

1. Technical Field
The present invention provides a catalyst system for the polymerization of olefins that include the combination of a titanium catalyst with an electron donor compound of the formula: ##STR2## wherein R.sub.1 is an alkyl or cycloalkyl group containing a secondary carbon atom attached to the silicon atom; R.sub.2 and R.sub.3 are alkyl or aryl groups; and R.sub.4 is an alkyl or cycloalkyl group with a secondary carbon atom attached to the silicon atom, R.sub.1 and R.sub.4 can be the same or different.
2. Description of Prior Art
Catalyst systems for the polymerization of olefins are well known in the art. Typically, these systems include a Ziegler-Natta type polymerization catalyst; a co-catalyst, usually an organoaluminum compound; and an electron donor compound. Examples of such catalyst systems are shown in the following U.S. Pat. Nos.: 4,107,413; 4,294,721; 4,439,540; 4,115,319; 4,220,554; 4,460,701; and 4,562,173; the disclosures of these patents are hereby incorporated by reference. These are just a few of the scores of issued patents relating to catalyst and catalyst systems designed primarily for the polymerization of propylene and ethylene.
A Ziegler-Natta type polymerization catalyst is basically a complex derived from a halide of a transition metal, for example, titanium, chromium or vanadium with a metal hydride and/or a metal alkyl that is typically an organoaluminum compound. The catalyst is usually comprised of a titanium halide supported on a magnesium compound complexed with an alkylaluminum.
The development of these polymerization catalysts has proceeded seemingly in generations of catalysts. The catalyst disclosed in the patents referenced above are considered by most to be third generation catalysts. With each new generation of catalysts, the catalyst properties have improved. Particularly, the efficiencies of the catalysts, as expressed in kilograms of polymer product per gram of catalyst in two hours, have increased from the 1-3 range to the 10-12 range and beyond. Catalysts have been developed that not only have higher efficiencies but also retain their activity over a longer period of time, thus being able to produce more polymer product over the life of the catalyst. Any increase in the efficiency and life of the catalyst leads to lower costs due to lower catalyst consumption, and it also lowers the capital expenditures in building and operating a plant as the size of the reactors are lowered for specific plant capacities and the reactor residence time is lowered. A higher efficiency also leads to a cleaner polymer product thereby avoiding the need to wash or treat the product to remove catalyst ash residuals.
In addition to the improved catalysts, improved activation methods have also lead to increases in the catalyst efficiency. A most recent discovery includes a process for pre-polymerizing the catalyst just prior to introducing the catalyst into the reaction zone. This process is disclosed in U.S. Pat. No. 4,767,735 the disclosure of which is hereby incorporated by reference.
In addition to the development of new catalysts and new reaction processes, a discovery of a more appropriate co-catalyst or electron donor to go with the new generation of catalysts in forming a total catalyst system would be of great benefit to the polymerization art especially if it lead to dramatic increases in the efficiency of the catalyst system and to improved quality control of the polymer product. In such a total catalyst system, a co-catalyst activates the catalyst and provides the initiation of a polymer chain.
The co-catalyst that works well with the new generation catalysts is an organoaluminum compound, most typically triethylaluminum (TEAl) or another trialkylaluminum, such as triisobutylaluminum. Examples of other useful organoaluminum compounds include an alkylaluminum dihalide, trialkoxyaluminum and a dialkylaluminum halide.
An electron donor compound is used in the polymerization reaction to reduce the atactic form of the polymer thereby giving control of and increasing the production of isotactic polymers. Although a broad range of compounds are known generally as electron donors, a particular catalyst may have a specific compound or group of compounds with which it is especially compatible. Discovery of an appropriate type of electron donor which gives significant increases in catalyst efficiency as well as improved control of the isotactic index of the desired polymer product and other properties of the product would be highly advantageous. One such group of electron donors are disclosed in U.S. Pat. No. 4,927,797.
The present invention comprises another such discovery. It has been surprisingly discovered that a specific group of silane compounds serving as electron donors in combination with a particular type of catalyst results in significant increases in catalyst efficiency over the previously known efficiencies for this particular type of catalyst as well as other known catalyst systems.

Catalyst system for the polymerization of olefins


The present invention relates to systems, compositions, and methods for the synthesis and use of imaging agents, or precursors thereof. An imaging agent precursor may be converted to an imaging agent using the methods described herein. In some cases, the imaging agent is enriched in 18F. In some cases, an imaging agent may be used to image an area of interest in a subject, including, but not limited to, the heart, cardiovascular system, cardiac vessels, brain, and other organs. In some embodiments, methods and compositions for assessing perfusion and innervation mismatch in a portion of a subject are provided.

Heart failure (HF) is defined as the inability of the heart to supply peripheral organs with sufficient blood flow. It may be characterized by a hyperadrenergic state whereby increased systemic levels of norepinephrine (NE) and increased local spillover of catecholamines occur. The condition afflicts increasingly more people each year and is a common end-stage of many cardiac diseases and conditions including myocardial infarction, pressure/volume overload, viral myocarditis, toxic cardiomyopathy, valve failure, and other abnormalities. The resultant myocardial damage, in conjunction with neurohormonal and cytokine activation, stimulates chamber remodeling which is the initial phase of heart failure. This remodeling process results in decreased overall myocardial efficiency and eventual progression to clinical HF. To date, however, no cure for the condition exists, thus early diagnosis is a key factor in its management and long-term prognosis. An imaging agent that identifies subjects in early HF would thus enable treatment and life-style improvements for patients living with the condition.
Myocardial damage may also occur following tissue insult (e.g., a myocardial infarction), whereby innervation and perfusion defects may form in a portion of the subject (i.e. a portion of the heart). In certain cases, the size of the defect areas, as detected by imaging, could be different (e.g., regional mismatch) and may be associated with an increased probability for cardiac arrhythmia as well as other conditions.
Accordingly, improved compositions, methods, systems, and apparatuses are needed for the synthesis and administration of imaging agents (e.g., for imaging the heart).

Compositions, methods, and systems for the synthesis and use of imaging agents


Lotion pump has a stepped piston telescoping inside a stepped body to define a pumping chamber. The piston has in its wall inlet and discharge apertures, one above the other, to the pumping chamber. A stem integral with the actuator has a sealing head inside the piston which shuttles up and down between positions at which it covers one aperture or the other. Shuttling is implemented by lost-motion between the actuator spout/stem and piston. A spring urges the stem up at all times. The actuator can be turned to lock the head over the discharge aperture by nullifying the lost-motion. Further turning can lock the stem in lockdown position. One-directional turnback can liberate the head and unlock the lockdown. Detents control sequence of unlocking.

The Cater U.S. Pat. No. 5,284,276 issued Feb. 8, 1994, discloses a meritorious pump for lotions or the like including a tubular main piston having an outward flange and seal. A stepped cylindrical pump body telescopingly receives the piston to define a pumping chamber. The piston has a unitary tubular upward axial outlet provided with a valve seat at its lower end. Adjacent and below the valve seat the wall of the piston is apertured. An actuator spout/stem, assembled as a single fixed-together, rigid unit, extends down centrally through the tubular upward outlet and seat. The lower end of the stem is formed with a valve head inside the piston in sealing engagement with the piston wall and adapted to rise to seat on the valve seat.
There is a lost-motion space between the actuator/stem and the piston so that, upon depression of the actuator, the stem drops with respect to the piston and the valve head unseats and moves below the aperture in the piston wall before the piston starts to move down. Continuing the same downward stroke, the actuator pressurizes liquid in the pump chamber and forces it out the aperture up through the valve seat and out the actuator spout.
A spring urges the actuator/stem up on the return stroke. The stem first raises up inside the piston, again opening the lost-motion space and forcing the head to seat on the valve seat and opening the aperture in the piston wall below the head. As the head engages a shoulder on the piston, the continued upward force of the spring then raises the piston. As the piston raises, it creates a vacuum in the pumping chamber, drawing lotion up through a dip tube at the lower end of the pump body, into the piston and through the aperture into the chamber ready for the next downstroke.
Under an improvement of the Cater pump disclosed in the pending patent application Ser. No. 08/902,027 filed Jul. 29, 1997, now U.S. Pat. No. 5,839,617, issued Nov. 24, 1998 and assigned to the assignee of this application, and incorporated hereinto by reference, the above-described valve seat is replaced by a second aperture in the piston wall above the aperture described. The stem head is in the form of a peripheral bi-directional fin-type seal which moves during the exercise of the lost-motion from a first position wherein the upper aperture is covered and the lower aperture uncovered to a second position wherein the lower aperture is covered and the upper aperture uncovered.
By having both apertures at the same diameter on the wall of the piston, manufacture is simplified and leaks are less likely. The head may have a peripheral seal of a single diameter. The improved arrangement better accommodates dimensional variations and does not require such precise molding. Also, finned-type seals are flexible and are more forgiving of dimensional variations. The clogging of the valve with a vertical beveled seating surface is not a concern.
In addition, the resulting structure permits separate apertures for the pump chamber inlet and discharge flow. Having separate apertures for the opposite flows, into and out of the pumping chamber, makes simpler flow paths and improves the efficiency of the pumping action in this relatively short-stroke application.
In a preferred version the two apertures may be in the form of a single elongated window, the upper portion of which, when exposed, constitutes the discharge and the lower portion, when exposed, constitutes the inlet of the pumping chamber. In the windowed version, the fin-type seals do not encounter the transverse edges of apertures which can cause wear. These two arrangements--the two separate apertures and the elongate window--are regarded as equivalent.
In another Cater U.S. Pat. No. 5,335,830 issued Aug. 9, 1994 incorporated hereinto by reference, a pump of this genre is provided with means for locking the stem with the head in a first position covering the discharge aperture. This comprises a step up in the lost-motion slot so that when the actuator is turned, the abutment surface on the actuator engages the step, nullifying the lost-motion, and the stem thereafter does not lower with respect to the piston, and the discharge is effectively "locked" closed. The '830 patent also provides an inward tooth on the retainer and an upward shoulder near the top of the piston. When the piston is pushed down and turned by the actuator, the shoulder is engaged by the tooth and the piston and actuator is locked down as is preferred for shipment.
It is an object of the present invention to provide means to give the consumer a tactile "feel" or snap when the locks are engaged.
Another object is to provide for a type of pump as shown in Cater U.S. Pat. No. 5,335,830 means assuring that the lockdown is not released until the means for disabling the discharge valve is nullified so that when the pump actuator rises from lockdown position the pump is fully operative.

Pump dispenser having a locking system with detents


A test system for use in testing Aircraft Rescue Fire Fighting and Structl Pumper vehicles equipped with fire fighting foam distribution systems. The dye piping arrangement for the test system uses a dye concentrate and water mixture which are delivered into the dye water foam free test system through a three way ball valve, a proportioner and eductor. Fluid flow through the eductor generates a vacuum or negative pressure within the eductor. The dye concentrate from a dye storage bottle is then suctioned into the foam distribution system by the negative pressure within the eductor. A needle valve, check valve and a dye solenoid valve are included in the system. The needle valve meters the amount of dye suctioned into the dye water foam distribution system. The check valve prevents any fluids from back flowing into the dye concentrate tank. The normally closed dye solenoid valve is remotely operated by an ON-POWER OFF-OFF three position switch. The switch is turned ON to provide for dye concentrate flow in the system. A digital monitor is also provided for use by the operator to read flow rate in gallons per minute during system operation. The dye concentrates used during testing are environmentally benign and biodegradable.

1. Field of the Invention
The present invention relates generally to fire fighting systems for use in fighting and extinguishing hydrocarbon and other flammable liquid fires. More particularly, the present invention relates to a foam free test kit for testing Aircraft Rescue Fire Fighting and Structural Pumper vehicles equipped with fire fighting foam distribution systems that must be routinely tested to ensure these systems operate correctly during fire fighting missions.
2. Description of the Prior Art
Presently, Aqueous Film Forming Foam, which is commercially available, and is defined in Military Specification MIL-F-24358, is the most commonly used fire fighting foam currently on the market. Aqueous film forming foam, is a very effective fire fighting foam for extinguishing hydrocarbon and other flammable liquid fires. Aqueous film forming foam has the quality of being able to spread an aqueous film on the surface of hydrocarbon liquids, enhancing the speed of extinguishment.
Aqueous Film Forming Foam are particularly advantageous in that they are designed to be used with water or seawater. When proportioned with water and applied with conventional foam or water/fog equipment, foam is generated. The foam spreads over the surface of the burning material forming a blanket in the manner of conventional foam. An aqueous solution drains from the foam bubbles and forms a vapor sealing film that floats on the surface of the burning matter and suppresses any volatile vapors, sparks, or the like.
The U.S. military, including the Navy, procures several hundred thousand gallons of Aqueous Film Forming Foam annually for use with shipboard fire fighting systems, aircraft hanger automated sprinkler systems, fire trucks, and fire fighting training and equipment testing. The amount of Aqueous Film Forming Foam used for equipment test and fire fighting training by the military is about 20 percent of the annual purchase of Aqueous Film Forming Foam.
There is a need to test fire fighting systems, especially crash fire rescue vehicles, which use Aqueous Film Forming Foam since these systems are not very reliable. These systems tests conducted monthly, weekly and sometimes daily to insure that the fire fighting systems are operating effectively and efficiently.
The frequent testing is creating a problem environmentally. Aqueous Film Forming Foam includes two components fluorocarbon surfactant and butyl carbitol which are toxic to shellfish and other organisms. Because of the environmental problems associated with Aqueous Film Forming Foam, foam waste water discharge on to the ground and to waste treatment facilities is prohibited.
Further, the cost of containment facilities to collect and/or treat hazardous waste and the disposal cost of Aqueous Film Forming Foam are preventing the timely testing of fire fighting equipment in accordance with the National Fire Protection Association fire code standards.
Since an environmentally safe formulation of Aqueous Film Forming Foam will not be commercially available in the immediate future, there is a need to develop a test system for the testing of fire fighting equipment which is effective, efficient and highly reliable and does not require the use of Aqueous Film Forming Foam during the test.

Foam free test system for use with fire fighting vehicles

The United States of America as represented by the Secretary of the Navy


A multilayer ceramic package 200 with a center ground via 202 for size reduction is disclosed. Package 200 includes dielectric layers 204A-204G each having a major surface 206. The package also includes an input electrode 208 and an output electrode 210 as well as a top ground plane 212 and a bottom ground plane 214. Package 200 includes a substantially spiral transmission line structure made from electrodes 216. Package 200 also includes a ground via 202 extending vertically through the plurality of dielectric layers 204A-204G. The center ground via 202 is substantially centered inside the substantially spiral transmission line structure and electrically isolated therefrom and connected to the top ground plane 212 and the bottom ground plane 214.

The placement of transmission lines for signal propagation through the various layers of a multilayer ceramic package is well known in the art. Such transmission lines are typically in the form of a conductive paste material (such as silver, gold, palladium, platinum or other metals) which is screen printed onto the layers of green ceramic tape which are then fired to form a dense, ceramic package.
Also of great interest to a designer of multilayer ceramic packages are the use of small holes in the sheets of ceramic, called vias, which are also filled with a conductive material. The vias serve the purpose of connecting the transmission lines on the various layers of ceramic through the multilayer package. Aside from merely connecting transmission lines on consecutive ceramic sheets, vias may also be used to connect the top and bottom ground planes in a ceramic package, for example. This is oftentimes necessary in order to keep the ground planes at equal potential. In any event, the strategic placement of vias and transmission lines in the ceramic package is one of the primary responsibilities of a multilayer package designer.
There are numerous factors which must be considered in the design of these multilayer packages. Printed lines and vias typically come in sizes and spacings that are standard to the industry. Printed lines and spacings have practical limitations. For example, 5 mil lines and 5 mil spacings are now readily achievable using typical multilayer processing equipment. Moreover, via diameters are also set by industry standards. Vias are typically 10 mils in diameter with the current technology. Of course, via diameters for various tapes will be a function of the tape thickness. Stated another way, for a given tape thickness, only certain sized vias may be properly filled with a conductive material.
If a via is too large, it may require a prohibitive amount of conductive paste to be properly filled and it may further weaken the mechanical integrity of the package. Conversely, if a via is too small, it may not be easily filled and it may cause a break in the conductive path which forms the transmission line.
Another concern is that by placing ground vias and transmission lines in too close a proximity to each other, they may interfere or interrupt the signal itself. For example, in a multilayer ceramic filter package, poor placement of transmission lines and vias may result in degradation of certain electrical properties such as insertion loss, return loss, or the Q (quality factor) of a transmission line. Poor placement of transmission lines and vias may also result in undesirable coupling, unintended electrical shorts, and unacceptable power requirements.
As is described above, the design of a multilayer package may be a complex process and formidable challenge. All of this is further complicated by the fact that the telecommunications industry is constantly seeking smaller packages, which have lower profiles and smaller package dimensions. Thus, designers are being forced to employ innovative designs to meet ever tightening specifications.
FIG. 1 shows a multilayer ceramic package 100 which is representative of a multilayer package found in the prior art. Referring to FIG. 1, package 100 is made from a set of sheets of ceramic material 102 which are laminated together to create a multilayer package. Patterns of conductive material are screen printed on to the various layers of the sheets of ceramic material to create a transmission line structure 104. Four vias 106A, 106B, 106C, and 106D form ground vias which connect a top ground plane 108 to a bottom ground plane 110. Significantly, the four ground vias 106A, 106B, 106C, and 106D are located outside and around the periphery of the transmission line structure.
FIG. 4A shows a plan view of a multilayer ceramic package also having ground vias outside a transmission line structure as is found in the prior art. Referring to FIG. 4A, a multilayer ceramic package 400 is provided. On one dielectric sheet 402, a printed pattern 404 is deposited. Other printed patterns, for example 405 shown as a dashed line in FIG. 4A, are printed on other layers of the multilayer ceramic package 400. The printed patterns are connected to form a transmission line structure. Four ground vias 406 are located around the outside of the transmission line. It should be noted that the area 408 internal to the transmission line does not contain any ground vias and remains as unused real estate on the dielectric sheet 402.
A multilayer ceramic package design in which a ground via is strategically placed through the center of another transmission line structure, namely, a substantially spiral shaped transmission line structure, which reduces the overall size of the multilayer package without adversely effecting the electrical performance of the package and which maintains the structural integrity of the package and which can be achieved using conventional multilayer processing techniques would be considered an improvement in the art.

Multilayer ceramic package with center ground via for size reduction


A robot control apparatus with great safety is provided by detecting access of a teacher to a robot and automatically reducing the operating speed of the robot when the teacher accesses the robot. The robot control device equipped with a pendant (10) to be manipulated by a teacher, for controlling the operation of a robot on the basis of an operation command from the pendant (10), includes a detecting device (8) for detecting the position of the teacher; a signal processing unit (11) for receiving a signal from the detecting device to produce the position information of the teacher; and a limited speed selecting unit (12) for selecting the operating speed of the robot on the basis of the position information. The robot is controlled at the maximum speed set at the operating speed selected by the limited speed selecting unit (12) on the basis of the operation command from the pendant (10).

Now referring to the drawing, an explanation will be given of a conventional robot control apparatus. FIG. 12 is a view showing the configuration of the conventional robot control apparatus.
In FIG. 12, reference numeral 101 denotes a robot connected to a robot control apparatus 105. A working tool 102 for working is attached to the tip of a wrist of the robot 101. The robot control device 105 is connected to a pendant 106 employed to conduct the editing such as registering of a working program, or changing of a registered working program by operating the robot 101, performing registering of a position thereof or registering of a work. The robot control apparatus includes a safety shelf surrounding the operating range of the robot 101, a safety shelf door 108 to a gateway to the safety shelf, and a safety shelf door opening/closing detecting device 109 for detecting the opened/closed status of the safety shelf door 108. The safety shelf door opening/closing device 109 is connected to the robot control deice 105.
The working is done by controlling the robot 101 in a manner of moving the working tool 102 on the basis of the above working program for a work 104 fixed to a work holding device 103 installed in the vicinity of the robot 101.
In the position registering of the robot 101 which is a part of the working program, a teacher manipulates the pendant 106 to operate the robot 101 so that the working tool 102 attached to the wrist is positioned at a prescribed position relative to the work 104 and the position is registered in a storage member not shown within a robot controlling device through the operation of the pendant 106. The changing of the registered position of the robot 101 can be executed likewise.
In order to assure the safety of the teacher, the procedure in teaching will be explained below.
The teacher changes the operation mode of the robot into a teaching mode and opens the safety shelf door 108 to enter the safety shelf 107.
As regards the operation mode of the robot 101, its maximum operating speed of the robot in the teaching mode is limited by informing the robot control apparatus of the facts that the operation mode is in the teaching mode and the safety shelf door opening/closing detecting device 109 is producing an opened status signal of the safety shelf door 108.
The maximum operating speed in this teaching mode is limited to limited to 250 mm/sec in an end effect unit.
Next, in positioning the working tool 102 to a prescribed position of the work 104, the robot 101 is operated by manipulating the pendant. At this time, the teacher must pay an attention to the robot 1, working tool 102, work holding device 103, work 104 and peripheral devices of these components.
In order to assure the safety of the teacher himself from the operation of the robot 101 not intended by the teacher due to an erroneous manipulation of the pendant 106, the maximum operating speed in the teaching mode is limited. Thus, the teacher performs the teaching at a position apart from the robot 101 or work 104 so that he can perform an evading action against the inadvertent operation of the robot 101 during teaching.
(Prior Art 1)
However, according to the shape and size of the work 104, the shape of the working tool 102, an the arrangement of the work holding device 103 and peripheral devices, as the case may be, the teacher must comes near the robot 101 or work 104 for teaching. In a conventional robot control apparatus, in such a case, in order that the teacher can take an evading action against the inadvertent operation of the robot 101 due to the erroneous manipulation, setting of the pendant 106 is made to reduce the maximum operating speed of the robot 101. Thereafter, the teacher performs the teaching.
On the other hand, in a product manufacturing factory where a plurality of robots are installed, the teaching for the robots is individually performed. However, as the case may be, a plurality of persons simultaneously perform the teaching in order to reduce the teaching time. In this case, the individual teacher pays an attention to the movement of the robot which is an object for teaching and a working tool attached to the robot or their interference with the peripheral devices, but pays less attention to the robot which is not an object for teaching and its peripheral devices.
Also in the case where the plurality of robots are controlled by a single robot control apparatus, as in the case described above, less attention is paid to the matters which are not the object for teaching.
If the operator stands outside the operation region of each robot, no interference occurs between the operator and the robot. However, where the teaching area difficult to confirm visually is taught or the point of teaching is finely adjusted, the operator comes near the robot. In the large-scale product manufacturing factory, the plurality of robots come near one another. Therefore, when the operator accesses a certain robot, he will enter the operation region of the other robots.
In such a case, between the first operator teaching the first robot and the second operator teaching the second robot, because of the operation based on the subjective impression or carelessness by the second operator, the second robot may give serious injury to the first operator through the operation directed to the first operator who stands within the operation region of the second robot or interference and collision with him.
Also in a production system in which a plurality of robots are controlled by a single robot control apparatus, where an operator performs teaching in an operating range of the plurality of robots, because of the operation based on the subjective impression or carelessness by the operator, as in the case, there is a danger that the robot which is not the object for teaching gives serious injury to the operator through the operation directed to the operator and or interference and collision with him.
(Prior Art 2)
In a conventional robot control apparatus, these inconveniences was dealt with by interrupting the power source of driving the other robot than the operating object, thereby braking each of axial motors.
(Prior Art 3)
As still another prior art, the Unexamined Japanese Patent Application Publication No. Hei11-165291 discloses a method in which while an industrial robot is operating, when a man or object enters the operating range of a robot, this is detected by a sensor, and a warning is issued to prevent an accident from occurring.
(Prior Art 4)
Further, the Unexamined Japanese Patent Application Publication No. Hei10-264080 discloses a method in which an operation abnormality detecting index for detecting abnormality in a moving speed, a moving acceleration, moving direction and moving position or abnormality in the angular speed of a wrist axis is created by CPU, and when the abnormality is detected as a result of comparison of the detecting index with a reference value, a robot is stopped.
In the prior art 1, when the teacher performs the teaching for the robot in access thereto, because of his desire in the improvement in an operation efficiency and forgetting of setting, as the case may be, he may operate the robot and perform the teaching therefore without reducing the maximum operating speed of the robot. In this case, if the pendant is erroneously manipulated, the robot makes the operation not intended by the teacher so that the teacher is surprised. Where the robot further comes near the teacher, he does not have a time to evade it.
The prior art 2 provides the method for surely not operating the robot by the brake attached to each axis by interrupting the driving power source of the other robot than the object for teaching. However, a plurality of persons cannot simultaneously perform the teaching in order to shorten the teaching time. This leads to a possibility of difficulty in startup of a product manufacturing factory. Further, it is actually impossible to teach the working by cooperation by a plurality of robots.
The prior art 3 provides a method for preventing an accident from occurring by issuing a warning when the person or object enters the operation range of the robot while the robot is operating. This method, if the robot is operating for product manufacturing, is an efficient means. However, during teaching, the operator frequently performs the teaching in the operation region of the robot. Therefore, whenever the warning is issued, the operation for continuing the teaching such as a releasing operation is required, thus leading to attenuation of the teaching efficiency.
The prior art 4 provides a method of detecting that the robot has made an abnormal operation to stop the robot. This abnormal operation is the movement to the direction different from a designated direction and deviation from a designated path. This method detects such abnormal operation to stop the robot. Further, the abnormal operation will occur owing to the erroneous operation of components within the control apparatus due to the temperature environment and electromagnetic environment around the robot or the interference status between the robot and peripheral devices. This method is an efficient means for preventing the abnormal operation from continuing. However, the operation not intended by the operator of the robot in a teaching scene is mainly attributable to the erroneous operation. When the erroneous operation occurs, the robot control apparatus cannot determine whether or not the designated moving speed and moving path of a robot control point have been intended by the operator. Thus, the detection in this system is made impossible, thereby making it impossible to stop the robot before the robot gives an injury to the operator.
As described above, the conventional robot control apparatus has a problem that it is difficult to assure the safety of the operator when performing the teaching involved with the robot operation in access to the robot.