The process of mitigation of spacecraft surface charging using polar molecules is invented. There exists a class of polar molecules which are electro-negative. This class includes the halocarbons, and includes the fluorocarbon refrigerants. They readily pick up electrons and become negatively charged molecules. In this invention, neutral polar molecular liquid is sprayed in fine mist form onto negatively charged spacecraft surfaces. The molecules pick up the electrons and evaporate away with the electrons.

The invention relates generally to systems for protecting spacecraft from hazardous space plasma environment, and more specifically it relates to a new kind of system for the mitigation of spacecraft surface charging using polar molecules. There exists a class of polar molecules which are electro-negative. This class includes the halocarbons, and includes the fluorocarbon refrigerants. They readily pick up electrons and become negatively charged molecules. In this invention, neutral polar molecular liquid is sprayed in fine mist form onto negatively charged spacecraft surfaces. The molecules pick up the electrons and evaporate away with the electrons.
Charging of spacecraft in the space plasma environment may be hazardous to the health of on-board electronics. It may affect telemetry, navigation, operations, and even the survivability of spacecraft, and degrade scientific measurements. Spacecraft charging may be due to natural or artificial causes. Natural charging is due to the interaction between a spacecraft and its space plasma environment. Artificial charging is due to beam emissions, for example. In the geosynchronous environment, a spacecraft is often charged negatively during eclipse.
The task of providing spacecraft charging protection using technology is alleviated by the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 5,594,325 issued to David Manner;
U.S. Pat. No. 4,691,159 issued to Ahrens et al.;
U.S. Pat. No. 4,899,269 issued to Rouzies;
U.S. Pat. No. 5,394,075 issued to Ahrens et al.;
U.S. Pat. No. 5,444,358 issued to Delepaunt;
U.S. Pat. No. 5,451,858 issued to Van Duyne et al.
The above-cited references describe patented space radiation protection systems. The Manner patent describes the use of spacecraft power systems to mitigate spacecraft charging effects. Geosynchronous spacecraft have a history of charging anomalies. Conventional passive protection measures are often complex and costly.
The present invention is a system for mitigating spacecraft charging by means of polar molecules. A polar molecule is a molecule possessing a permanent electric dipole moment. Molecules containing atoms of more than one element are polar except where forbidden by symmetry; molecules formed from atoms of a single element are nonpolar.
The present invention is based on the theory that the positive ions returning to the spacecraft neutralize the excessive negative surface charge and the electrons leaving from the spacecraft carry away negative charge. Using ions or electrons alone would cause differential charging, meaning different surfaces attaining different charging levels. On one embodiment of the invention a polar molecule liquid is stored in a container. A heating coil is inside. The heater coil is capable of heating the liquid to temperatures near boiling. The liquid flows along a tube through a control knob to atomizer sprayer, which is mounted on a movable arm on a tower. The lengths of the towers and arms equal the radius of the spacecraft approximately.
To operate the device, the movable arm moves into a desired position to aim the polar liquid vapor/droplet spray onto a charged spacecraft surface. The vapor/droplets are neutral initially. There the droplets act as electron scavengers and become negatively charged droplets. As they evaporate to small sizes, they eventually burst into smaller droplets taking the electrons away.
The control knob can be switched on or off by a remote command from the ground. When the negative charging level of the spacecraft or a spacecraft surface reaches a certain level, the ground command can optionally turn the mitigation device on. When the level falls to a certain level, the ground command can optionally turn the mitigation device off. Alternatively, it can be turned on or off automatically by linking it to a charge sensor. When the sensor senses a critical charging level, it can send a command to turn on or off the device automatically.

Mitigation of spacecraft charging by means of polar molecules

The United States of America as represented by the Secretary of the Air Force


The invention is directed to a ceramic material for use in thermal barriers for high temperature cycling applications and high temperature abradable coatings. The material is an alloy formed predominantly from ultra-pure zirconia (ZrO2) and/or hafnia (HfO2) that has uncharacteristically high sintering resistance to achieve a high service lifetime and low thermal conductivity to achieve high operating temperatures. In the material, oxide impurities such as soda (Na2O), silica (SiO2), alumina (Al2O3), titania (TiO2), hematite (Fe2O3), calcia (CaO), and magnesia (MgO) make up no more than 0.15 weight percent. The invention provides materials to produce a coating structure so that the changes in the coating microstructure over the in-service lifetime are either limited or beneficial.

1. Field of the Invention
The invention relates to ceramic materials for thermal barriers and abradable coating systems in high temperature and high temperature cycling applications, and more particularly to ultra-pure zirconia materials for use in thermal barrier and abradable coating applications.
2. Description of the Related Art
Superior high-temperature properties are required to improve the performance of heat resistant and corrosion resistant members. These members include, for example gas turbine blades, combustor cans, ducting and nozzle guide vanes in combustion turbines and combined cycle power plants. Turbine blades are driven by hot gasses, and the efficiency of the gas turbine increases with the rise in operational temperature. The demand for continued improvement in efficiency has driven the system designers to specify increasingly higher turbine operating temperatures. Thus, there is a continuing need for materials that can achieve higher operational temperatures.
Thermal barrier coatings are used to insulate components, such as those in a gas turbine, operating at elevated temperatures. Thermal barriers allow increased operating temperature of gas turbines by protecting the coated part (or substrate) from direct exposure to the operating environment. An important consideration in the design of a thermal barrier is that the coating be a ceramic material having a crystalline structure containing beneficial cracks and voids, imparting strain tolerance. If there were no cracks in the coating, the thermal barrier would not function, because the differences in thermal expansion between the metal substrate system and the coating will cause interfacial stresses upon thermal cycling that are greater than the bond strength between them. By the creation of a crack network into the coating, a stress relief mechanism is introduced that allows the coating to survive numerous thermal cycles. Repeating crack networks are typically imparted into the coating on varying space scales by manipulating the thermodynamic and kinetic conditions of the manufacturing method, and different structures known to perform the coating task have been optimized likewise. In addition to this, cracks are also formed during service, so the structure formed upon coating manufacture changes with time, depending on the starting material phases in the manufactured coating and thermal conditions during service.
Another design factor determining coating lifetime is the sintering rate of the coating. When the coating is cycled above half of its absolute melting temperature, the coating begins to sinter causing volume shrinkage. As the coating shrinks, the stress difference between the coating and substrate increases. At a certain amount of shrinkage (which varies depending on the type of structure and thermal conditions during service), the stress difference exceeds the bonding strength of the coating and it becomes detached. Decreasing the sintering rate of the thermal barrier increases the amount of time before the catastrophic shrinkage is experienced, so it can become a major design consideration. For high purity zirconia alloys, the onset of sintering commences at temperatures above 1000° C.
Historically, high temperature thermal barrier coatings have been based on alloys of zirconia. Hafnia may also be employed due to its chemical similarity to zirconia, but is generally cost-prohibitive. Hafnia also is typically present in most zirconia materials in more than trace amounts due to difficulty in separating the two oxides. Zirconia and/or hafnia have the following combination of desirable properties that other known ceramic systems do not possesses for the application. First, zirconia alloys have some of the highest melting points of all ceramics, and this means theoretically some of the highest temperatures for which the onset of sintering occurs. Second, zirconia alloys have one of the lowest thermal conductivities of all ceramics. Third, zirconia has one of the highest coefficients of thermal expansion of all ceramics, so it is most compatible with transition metal alloys during thermal cycling.
Zirconia alone cannot fulfill the coating requirements because it undergoes a phase transformation from tetragonal to monoclinic during thermal cycling. This transformation is presumed to cause a detrimental volume change resulting in large strain differences between the coating and the substrate. When the resulting stresses exceed the bond strength of the coating to the substrate, the coating will detach. For this reason a phase stabilizer is added to the zirconia and/or hafnia, such as yttria, which suppresses the tetragonal to monoclinic phase transformation.
Thermal spray abradable coatings are commonly used in gas turbine applications. Abradable coatings are designed to preferentially abrade when contact is made with a mating part. These coatings have low structural integrity so they are readily abraded when they come into contact with a moving surface with higher structural integrity (such as the blade of a turbine). The coatings are designed so as not to damage the mating surface. In many applications abradable coatings are subject to the same thermal cycling conditions as the thermal barriers described above. Thus, there is a continuing need for materials suitable for abradable coatings that can achieve higher operational temperatures.
Some previous efforts to improve coating life have focused on the coating material and microstructure upon entry into service. However, the heat cycle of in service parts also causes cracks throughout the service life of the part. Thus, the microstructure formed upon coating manufacture changes with time, depending on the starting material phases in the manufactured coating and thermal conditions during service. Because a consistent optimal crack network is not typically maintainable throughout the service life of the part, coating lifetime is ultimately determined by the material selection and its manufacturing process. There remains a need in the art for a coating material, coating material manufacturing method, and coating manufacturing method that address the changes in the coating microstructure during its service lifetime.

Ceramic material for high temperature service


A system and method for delivering documents having dynamic content embedded over the worldwide Internet or a local internet or intranet. A data source is stored on a server computer connected to the Internet, the data source containing content in a form representing or reducible to names and corresponding values. Document templates are created by embedding dynamic tags and flow directives in markup language documents, the dynamic tags and flow directives containing one or more names of content stored in the data source. The document templates are stored on the server computer. The server computer can receive requests from client computers connected to the Internet, the requests identifying desired documents to be delivered. In response to such a request, the server computer selects one of the document templates corresponding to the desired document, populates the document template with content stored in the data source based on respective values of content corresponding to names in the dynamic tags and flow directives, and delivers the populated document to the client computer. The invention has particular application to HTML documents transferred over the World Wide Web.

This invention relates generally to a method and system for producing and delivering documents having embedded dynamic content. More particularly, the present invention relates to a method and system for producing world wide web page document templates by embedding dynamic tags and flow directives therein, populating the document templates with content stored in a data source, and delivering the populated documents over the Internet to clients requesting them.
The last few years has seen a rapid increase in usage of the worldwide network known as the Internet. This increase is particularly significant in the commercial arena. More and more businesses are recognizing the commercial potential for marketing, selling, and distributing products and services on-line, posting employment opportunities, and providing general corporate information and technical and product support. The bulk of this increased activity is taking place on the World Wide Web ("WWW" or "web"), a resource discovery tool for connecting documents or pages stored on networked computers by virtue of hypertext links. Although the architecture and operation of the web will be briefly summarized below, many resources are available for further background information on the Internet and the web, including December, J. and Randall, N., The World Wide Web Unleashed (Sams.net Publishing 1995) and Stanek, W. R., Web Publishing Unleashed (Sams.net Publishing, 1996).
Web documents are stored on web servers and are provided to client computers over the Internet upon receipt at the web server of a request for the document in the form of a uniform or universal resource locator ("URL"). The URL specifies the communications protocol by which the information is to be transferred and the Internet address of the host or web server upon which the document is stored. The URL may also specify a directory path and file name for the document. The communications protocol for the web is the hypertext transfer protocol ("HTTP"). Other communication protocols for other Internet communication tools include the file transfer protocol or FTP, Gopher, news for the Usenet, telnet, and mailto for electronic mail.
Documents or pages stored on web servers and available over the web are generally formatted in a markup language. Markup language web documents contain text and a number of tags which provide instructions as to how the text should be displayed (e.g., character and paragraph formatting, tables, forms, etc.), which text should be hyperlinked to other pails of the document or other documents, and where other types of content, including graphics and other images, video and audio segments, application programs or applets, image maps, and icons, should be retrieved from and displayed in the document.
One of the most commonly used standardized markup languages is the Hypertext Markup Language ("HTML"), currently available in several versions. Other standardized markup languages include the Standard Generalized Markup Language ("SGML") and Virtual Reality Modeling Language ("VRML"). Some markup languages, such as page definition languages, mark up web documents using a generally proprietary format which is specific to a particular commercial page display application program.
After a web page is transmitted from the web server to a client computer, a program referred to as a browser operates on the client's computer to interpret the tags and perform the formatting and other operations specified in the tags to display the text and other content in the document on the client computer's display. Many types of browser programs are available, including several variations of Mosaic, Netscape Communications Corporation's Netscape Navigator, Microsoft Corporation's Internet Explorer, TradeWave Galaxy's MacWeb, and Oracle's PowerBrowser, to name just a few. Different browsers and different versions of the same browser provide varying functionality in reading and displaying web pages and are operable on a wide variety of different platforms.
Because of the huge and ever increasing number of available web sites (which refers generally to the main or home page and ancillary or sub pages) competing for users' attention, companies recognize the importance of having well designed web sites which are informative, attractive, and user friendly. Much paper and electronic literature has been devoted to explaining techniques and styles for developing good web sites, and companies invest much time, money and effort to develop good, competitive web sites.
Despite its advances in recent years, several problems persist with the web and the Internet in general which may inhibit its continued growth as a useful commercial tool. One such problem is the lack of personalized attention in web sites to users and their specific needs and interests. For example, users accessing a merchant's web site all receive the same catalog displaying the same products at the same prices. However, users have their own particular interests and reasons for accessing a given web site. Because of the substantial time involved for users to download and review documents, users would prefer not to download an entire catalog in order to receive limited information of interest. For example, a user owning a IBM compatible personal computer would prefer not to have to download information regarding Apple compatible computers.
Conversely, in real world settings merchants prefer to enter into direct, one-to-one relationships with customers, and marketing which is more directed and focused towards each customer's interest is generally more effective and results in more sales. However, the almost anonymous nature of the web makes it difficult for merchants to establish that type of relationship on-line. Also, merchants frequently offer price discounts or special prices to certain customers, and otherwise provide individualized responses to customer's requests for assistance and information. Again, the web environment makes it difficult for merchants to offer such individualized attention to their customers.
A related problem is that the multiplicity of types of markup languages and, more significantly, types of browsers makes it difficult for web site developers to develop web pages that are compatible with all conceivable browsers users may be operating. This is particularly true for web pages employing enhanced features which are otherwise desirable to remain competitive and to show users that the web host is on the cutting edge. As a result, web pages often contain statements informing users that their web sites may only or may best be accessed with a given version of a given browser or may not be accessible with particular browsers. Alternatively, web pages contain hyperlinked lists of browsers which are supported by the web server, and users select one of the browsers on the list to hyperlink to a page which supports their selected browser. This adds time and inconvenience to the process of browsing the web and frequently annoys users.
Thus, a methodology is needed for providing web pages to users which are customized and individualized to each user's particular needs and interests. Preferably, this should be done in a manner which is transparent to the user, which does not require the user to search through and download multiple documents, and which does not require the web site developer to design and store a large number of web pages. The present invention provides such a methodology and solves these and other problems associated with the web to help make the web a more effective commercial tool.

Method and system for delivering documents customized for a particular user over the internet using imbedded dynamic content


An alternating current magnetic levitation transport system transporting a floating body made of conductive paramagnetic or nonmagnetic metallic material being levitated over alternating current electromagnets by making use of repulsion of an alternating electromagnetic field, comprises a tubular passage provided over the alternating current electromagnets which are spatially cut off from the outside wherein the floating body is levitated and transported. A cooling system made of a conjoined body of a thermoelectric cooling thermomodule and a liquid-cooled heat exchanger is provided in the transport system in contact with said tubular passage. This system can be favorably used in a clean environment where dust generation has to be avoided and the system can thereby provide more efficient transportation.

1. Field of the Invention
The present invention relates to a preferred transport apparatus or system to be used in the field in which an uncontacted transport of objects is required, such as a wafer transport equipment in a semiconductor production line wherein dust generation has to be avoided, a vacuum transport system wherein scattering of lubricant has to be prevented, and a transportation apparatus to be used in a high temperature atmosphere or the like. More specifically, the present invention relates to an alternating current magnetic levitation, transport system in which an object to be transported is mounted on a floating body and the floating body made of a conductive paramagnetic or nonmagnetic metallic material is floated and transported in a system over alternating current electromagnets disposed in rows.
2. Description of the Related Art
Conventionally, what is called a magnetic bearing composed of permanent magnets or electromagnets has been used as a bearing for a transport or transfer mechanism for objects (such as semiconductor wafer) in, for example, a semiconductor production process line wherein dust generation or scattering of lubricant is detested. In this system an object to be transported or supported is floated over a clearance without contacting anything by means of magnetic attraction or repulsion working between magnets or between a magnet and a magnetic material. As for the mechanisms of this kind, various researches and developments have been made and many of them have already been put in actual use.
However, among them magnetic bearings making use of electromagnets have such drawbacks as that they require control circuits for stabilizing intrinsically unstable attraction of magnets by means of electrical control although they have an advantage of small electric power consumption, or that many attachments, such as necessary gap sensors, are required. Especially, these control circuits have to be provided over the entire transport line in the case of a long distance transportation.
As a means to avoid the above-mentioned drawbacks, a necessary circuit and sensors may be mounted on a transported object. However, in this case a power source, such as batteries or the like, is required on the object and further a major problem occurs with respect to equipment that a charge or power supply system newly becomes necessary for operation over an extended period of time.
On the other hand, use of magnetic repulsion, in principle, makes the above-mentioned control devices unnecessary and has a great advantage as a transportation mechanism for a long distance in terms of the required equipment.
However, it is generally believed that a repulsion levitation mechanism composed of permanent magnets only is practically impossible, and at least one or more axes of its degrees of freedom must be stabilized by means of the above-mentioned control circuits.
On the contrary, it is theoretically confirmed that an inductive repulsion method using alternating current electromagnets can stably float and support objects by devising appropriate forms of floating bodies made of conductive materials. FIG. 11 shows such a method. In FIG. 11 (a) through (c), reference numeral 01 denotes an alternating current electromagnet, and 02 a floating body to be transported, for which a light and highly conductive material such as aluminum is suitable. An object desired to be transported is usually placed on this floating body 02.
In the composition illustrated in FIG. 11, when an alternating current flows in the aforementioned alternating current electromagnet 01, an alternating magnetic field is generated above the magnet. Because the floating body 02 is in this magnetic field, an alternating current called as an eddy current flows in the material (aluminum) of the floating body 02. The magnetic field generated due to this overcurrent is formed exactly in the repulsive direction to the magnetic field generated by the electromagnet, so that due to this repulsion a floating force indicated as Fl in the figure acts on the floating body 02.
Then the floating body 02 can be driven by means of a driving force F2 exerted thereon. This force F2 is produced by linear motor mode driving of the electromagnets disposed in rows as shown in FIG. 11 (b) and (c).
In FIG. 12, an object 03 to be transported is mounted on the floating body 02 in the apparatus shown in FIG. 11.
Described above is the transportation principle of an alternating current repulsion system. However, when this alternating current repulsion system is applied to vacuum transportation, such as in the wafer transport equipment in the semiconductor production system in which dust generation has to be avoided, it has previously been necessary to take such a measure as covering and fixing the electromagnets with resin to protect the dust generation from the electromagnets because the floating body transport passage and electromagnets are disposed in the same area. However, even if this protection measure is taken, it is deemed difficult to maintain a high grade vacuum because of a gas released from the resin when the above-mentioned electromagnets are placed in a vacuum atmosphere.
Further, the alternating current magnetic levitation transport system as shown in FIG. 11 and FIG. 12 has a problem of heat generation due to an electric current flowing in the floating body 2. As is generally known heat generation Q in a metal due to an electric current is given by EQU Q=I.sup.2 R, or Q=E.sup.2 /R
where,
Q=heat generated, PA0 I=electric current, PA0 E=electromotive force (voltage), and PA0 R=electric resistance.
Therefore, the temperature of the floating body 02 is changed when the heat equivalent to the heat generated (Q) is not removed. The temperature of the floating body 02 is elevated when the heat removal is insufficient, causing a thermal damage to the transporting object 03 or a thermal deformation and damage to the floating body 02, and normal operation becomes impossible.
As described above, the utilization of an inductive repulsion system using alternating current electromagnets for the vacuum transportation, such as the wafer transport equipment in the semiconductor production system in which dust generation is disliked, conventionally requires the countermeasures, such as, a means against dust generation or gas release from electromagnets, a means against heat generation in the electromagnets due to an electric current flowing therein, and a means against heat generation in the floating body caused by an induced electric current due to electromagnets. Especially, gas release from the electromagnets causes, in the case of a wafer transport equipment, for example, the composition of the wafer surface to deteriorate, resulting in a fatal yield reduction in the production of semiconductors while higher integration of semiconductor elements is now in progress.
Also, it is possible to cool a heated floating body by a cooled heat transfer surface. However, when transporting operation is restarted by turning on the alternating current electromagnets and the floating body is floated, the temperature of the floating body increases again, thereby the floating body needs to be cooled again by stopping the transporting operation. The smaller the frequency of operation stoppage is and the less the cooling (operation stoppage) time for cooling the floating body is, the better the operation performance of the system becomes. Therefore, further improvement of the cooling technology is required.

Alternating current magnetic levitation transport system


An integrated window design for optical transmission in combustion environments is described. The invention consists of an integrated optical window design that prevents and removes the accumulation of carbon-based particulate matter and gaseous hydrocarbons through a combination of heat and catalysis. These windows will enable established optical technologies to be applied to combustion environments and their exhaust systems.

Fossil and renewable energy fuels, such as oil, coal, gas and biomass, are burned or, in other words, combusted in order to produce energy. These combustible fuels may be utilized in internal combustion engines (such as spark ignited and compression ignition systems found in automobiles, trains, ships, planes, and generators), in turbine engines (used to power aircraft and ships), and in furnaces (such as burners, boilers, fluidized beds used in steam power plants).
The burning of combustible fuels to generate energy results in the generation of pollutants including CO, CO2, NOx (NO and NO2), particulate matter, sulfur compounds, and assorted hydrocarbons. These combustion pollutants are commonly exhausted to the atmosphere where they present a potential hazard to human health and the environment.
Monitoring of combustion processes and subsequent emissions within combustion chambers or their exhausts is extremely difficult because of the rapid build up of hydrocarbons and particulate matter on exposed surfaces within the combustion environment. It is vitally important to monitor these processes, however, in order to evaluate system parameters, optimize combustion performance, and provide feedback control, all of which are necessary to improve energy efficiency and limit pollutant emissions.
Many, if not all, of the emissions formed during combustion can be accurately and rapidly measured using standard optical methods (such as Fourier transform infrared spectroscopy and non-dispersive infrared analysis, for example). These technologies, however, require optical access to the exhaust stream of a combustion environment. Installation of a plain transparent optical access port or window into some component of the exhaust system would be futile because the build up of hydrocarbons and particulate matter would attach to and cloud the window on a frequent and regular basis. The accumulation of these contaminants on window surfaces is considered the primary barrier to the utilization of optical technologies in combustion and/or emission environments.
Most automotive emission sensors are solid-state devices that use a zirconia-based solid electrolyte to conduct oxygen atoms from one surface to the other. The response of these devices is dependent on the diffusion rate of oxygen atoms through the zirconia and this diffusion rate is limited due to the required thickness of the zirconia-based electrolyte. Because these sensors are diffusion limited, they have relatively slow time constants (>150 milliseconds) for producing data. In addition, since oxygen is the conducting medium, they are limited to the measurement of oxygen and some oxide gases (such as NOx), and therefore cannot be used to directly characterize hydrocarbons and particulate matter. These sensors also have poor resolution and are unable to measure concentrations below 10 parts-per-million.
It is highly desirable to measure hydrocarbons, particulate matter, and other gaseous emissions at time constants much less than 150 milliseconds. Optical-based sensors (such as those based on infrared spectroscopy) offer high speed (time constants <<150 milliseconds) and can be used to measure a range of pollutant species (including particulates) not detectable by currently available solid state devices. As noted earlier, many optical techniques are already well established and commercially available. The barrier to realizing optical diagnostic measurements lies with the constant fouling of the optical port, or window, due to the continual buildup of hydrocarbons and particulate matter.
During coal and oil combustion, visual monitoring takes place via portals in which clean air or an inert gas (such as nitrogen or argon) is constantly directed over the portal surface to maintain visibility. In spite of this, the portals nevertheless become contaminated over time and must be periodically cleaned. Another disadvantage of this technology is that a gas supply must be constantly directed over the portal. This necessitates a storage and supply system for the inert gas. A large percentage of the cost for these systems is associated with this gas usage.
Infrared detectors contain a detector that measures the intensity of infrared radiation. They are used to determine the presence of a flame during combustion (such as in gas/oil burners). Unfortunately, these detectors can also become contaminated with hydrocarbons and particulate matter and, as a result, must be frequently replaced. In fact, the accumulation of soot and/or hydrocarbons is considered a serious safety issue, since these detectors are considered unreliable when they become dirty.
As noted earlier, neither infrared detectors nor air guard portal systems are self-cleaning. Thus the combustion system must be stopped and/or at least partially dismantled in order for either an air guard portal system or an infrared detector to be cleaned or replaced on a regular basis.
In order to achieve maximum capability for any combustion/emission sensor system, one would need to install an optical access port, or window, containing an integrated self-cleaning system, into some component of the combustion/exhaust system. The self-cleaning capability of such a window would prevent and/or remove any buildup of hydrocarbons and particulate matter and thus maintain a clear optical access, or window, through which emissions may be measured.
U.S. Pat. No. 6,173,086 to Williams shows a vehicle window assembly that includes one or more resistance heating lines for electrically heating a section of the window area corresponding to a window wiper rest area. Williams' invention, however, would not work in the exhaust stream of a combustion environment because both hydrocarbons and particulate matter adhere too strongly to a surface to be wiped clean via mechanical action. Also, precision mechanical action would be limited if not impossible inside a combustion chamber, as the intense heat and pressure would interfere with mechanical movement and would likely severely damage any wiper assembly. Further, unlike the present invention which uses no mechanical action, Williams' invention centers around mechanical action. The present invention utilizes catalysis and thermophoretic action to prevent and/or remove hydrocarbon and particulate matter accumulation and maintain a clean surface.
U.S. Pat. No. 6,436,198 to Swain shows a method and apparatus for removing polymeric coatings from optical fiber by disposing the fiber within a low pressure environment and applying sufficient heat to volatilize at least a portion of the polymeric coating. This invention is, in essence, a vacuum furnace and therefore is unsuitable for use in a combustion environment, as one cannot achieve a vacuum during combustion. While Swain's invention does employ a heating grid, the present invention utilizes heat plus catalysis and Swain's invention uses heat plus vacuum.
U.S. Pat. No. 5,986,612 to Nagy shows a vehicle window antenna, comprised of a grid of conductive frit material affixed to the inner side of a window glass in a confined area above a window heating element comprising a grid of similar material similarly affixed and covering most of the window viewing area. While Nagy's invention utilizes a heating grid, the grid is not used to clean a surface, nor does Nagy's invention offer the application of catalysis in any way.
Accordingly, a need in the art exists for an integrated self-cleaning window assembly for monitoring gaseous and particulate matter emissions in a combustion environment while simultaneously preventing and removing the accumulation of carbon-based particulate matter and hydrocarbon condensation through a combination of catalysis and/or heat.

Integrated self-cleaning window assembly for optical transmission in combustion environments


A plastic wheel assembly (122, 222) and wheel mounting sleeve (127, 227) used to releasably secure the wheel (122, 222) onto an axle (123, 223). The wheel mounting sleeve (127, 227) includes an axle stabilizing opening (100, 200) positioned in an end wall (158, 258) of the sleeve which receives an axle outer end or axle stub (199, 299) that supports the axle (123, 223) against lateral loading and stabilizes it to reduce wobble, chatter and vibration. The opening (100, 200) permits visual confirmation of proper section of the axle outer end (199, 299) in the opening (100, 200). A universal axle (223, 223a) is also provided which can be used to couple wheels (122, 222) having shaped axle bores (139, 239) to the axle using wheel mounting sleeves (127, 227), as well as being used to couple wheels (420), having straight or substantially cylindrical bores (439), to the axle using conventional fasteners (450, 461, 470).

The use of plastic wheels on a variety of products has dramatically increased in recent years. One area where such plastic wheels have been widely employed is on wheeled refuse or garbage carts or bins of the type commonly employed by homeowners for their trash. Typically, these carts are formed of an injection, blow or rotationally molded plastic and have injection, blow, rotation or compression molded plastic wheels which are mounted on the ends of a metal axle by a hub member or push-on hat fastener (sometimes referred to as "pawl nut"). The wheel hub is hammered onto the end of the axle to hold the wheel in place. Removal of such plastic wheels in order to replace or repair the wheel or the cart has been difficult because the hammered push-on hat fasteners or hubs require special tools for their removal or essentially must be destroyed to remove them from the axle. Sometimes this process also damages the axles. Thus, more recently, wheel-mounting sleeve assemblies have been devised which snap-on to the axle to hold the wheel to the axle.
As the size of the axle and wheel are reduced, for example, when such wheel assemblies are used on wheeled toys, wagons, coolers or the like, the amount of material which can be employed in a wheel mounting sleeve to stabilize the coupling of the axle to the wheel decreases. Since such mounting sleeves often employ resiliently transversely displaceable fingers to lock or latch the wheel to the axle, the area of the sleeve which includes the displaceable finger tends to be somewhat less stable and less capable of supporting shifting or rocking along the axle and transverse loads on the axle. The stability decreases as the sleeve size decreases and there is less material to engage and hold onto, or latch to, the axle and to resist axial shifting and transverse loading in the area of the resiliently transversely displaceable fingers, which usually are located proximate an outer end of the axle.
Prior art snap-on wheel-mounting assemblies have been unduly complex, visually unappealing, and not well suited to the shock loading and vibration which is commonly encountered. They also are not easily adaptable for use on smaller axles and smaller wheeled products. Moreover, the cost of prior art snap-on couplings has been undesirably high, as has their rate of failure.
Most wheel mounting sleeves typically require a wheel having a central wheel bore which is formed with shoulders which cooperate with the sleeves to lock or latch the sleeve to the wheel. The sleeve further is formed to latch the sleeve to a circumferentially extending notch provided on axles in wide spread use in the industry.
As set forth in my U.S. Pat. No. 6,637,835, an improved axle has been devised which has a stub extension beyond the conventional notch that seats in a recess in the wheel mounting sleeve to stabilize the end of the axle in the sleeve. Wheeled product manufacturers, however, would prefer having an axle which can be used with standard wheels having straight (cylindrical) bores, as well as with wheel mounting sleeves and wheels with cooperating, stepped wheel bores. Thus it would be highly advantageous to provide a universal axle structure that can be used with any one of push-on hat fasteners, washer and cotter pin assemblies, hub inserts and wheel mounting sleeves.
Typical prior art wheel-mounting assemblies can be seen in U.S. Pat. Nos. 486,023, 2,978,277, 3,907,370, 5,215,356, 5,222,786, 5,277,480, 5,603,555, 5,716,107, 5,902,018 and 6,099,083 and in published European Patent Application No. 0 180 307.
U.S. Pat. No. 486,023 to Bermel discloses an axle nut used to secure a wheel on a somewhat involved axle structure. Another wheel retaining axle nut is shown in U.S. Pat. No. 6,099,083 that also is designed for use with a cooperatively formed and unique notched axle.
In U.S. Pat. No. 2,978,277 to Gaudry a two-piece hub assembly is used to secure a wheel on an axle stub. The two hub halves are forced together to simultaneously capture the head of the axle and a dove-tailed cross section of the wheel. This approach is based, in part, upon mating frictional engagement of the hub halves, but under the shock loading and high vibration which refuse carts, cooler and toys typically experience, frictional securement of components can be unreliable. The need for multiple hub pieces and an axle with an enlarged head, also is not desirable and the end of the axle is not supported well against transverse loading.
The wheel-mounting assembly of U.S. Pat. No. 3,907,370 to Bard employs a mounting sleeve which is keyed to slide over the keyed end of a specially formed axle. The sleeve mates with spokes in a wheel recess and is held in place by a washer and cotter pin. An annular cap is placed over the cotter pin and washer. This approach requires axle keying, a plurality of parts, the use of tools to secure and release the cotter pin and cap, and a laterally unsupported axle end.
A multiple piece hub assembly is shown in U.S. Pat. No. 5,716,107 to Parker et al. In this wheel-mounting assembly a retainer member is used to lock the wheel assembly on a groove or annular notch at the end of the axle. The hub cover is snapped into the wheel and then the wheel snapped onto the axle. Such notched or grooved axles are in wide spread use in connection with trash carts, but this assembly again requires multiple pieces and, in this case, special tools and tedious manipulation are required in order to release the resilient retainer ring fingers from the inside of the wheel so that the wheel can be removed from the axle. A similar snap-on hub assembly is shown in U.S. Pat. No. 5,215,356. In both U.S. Pat. Nos. 5,716,107 and 5,215,356 the wheel securing device is not a sleeve which extends through the wheel bore.
Four patents which employ sleeve assemblies formed for mounting through the wheel in telescoped relation over the axle are shown in U.S. Pat. Nos. 5,222,786, 5,277,480, 5,603,555 and 5,902,018. The devices of U.S. Pat. Nos. 5,222,786 and 5,603,555 have sleeves with at least one snap-acting, axle-engaging shoulder thereon which releasably retains the sleeve on the axle and at least one wheel-engaging shoulder retaining the wheel on the sleeve. As will be seen, however, both of the wheel-mounting sleeve assemblies in these patents are relatively complex and employ a plurality of pieces in order to secure the wheel on the axle. As the wheel and axle size reduces, therefore, these assemblies become more difficult to employ.
In U.S. Pat. Nos. 5,277,480 and 5,902,018 separate retainer devices are used with sleeves, but the outer ends of the axles are essentially unsupported and hub covers must be employed for safety and/or aesthetic reasons.
Finally, in European publication No. 0 180 307 collets are provided on an inwardly cantilevered stub of the wheel to grip a notch formed in the axle. No through-the-wheel sleeve is employed in this assembly.
Accordingly, it is an object of the present invention to provide a wheel assembly and wheel mounting sleeve having a minimum number of parts which can be used to mount plastic wheels to notched or grooved metal axles.
A further object of the present invention is to provide a plastic wheel assembly for a trash cart, wagon, cooler or other wheeled product which is economical to manufacture, easy to mount to the axle, and is durable, stable and capable of withstanding substantial shock loads, side-to-side shifting and vibration during normal use.
Another object of the present invention is to provide a universal axle assembly which can be used with conventional straight bore wheels and conventional fastening devices, as well as with wheel mounting sleeves for wheels with cooperatively formed wheel bores.
Still another object of the present invention is to provide an axle wheel mounting sleeve and wheel in which the assembly formation of the wheel is easier to accomplish and proper seating of the axle and securement of the wheel thereon can be confirmed.
The wheel assembly axle and wheel mounting sleeve of the present invention have other objects and features of advantage which will become apparent from, and are set forth in more detail in, the accompanying Drawing and following Best Mode Of Carrying Out The Invention.

This patent is subject to a terminal disclaimer.

Plastic wheel assembly, mounting sleeve and universal axle


An addition chain is first generated, and then an integer x is derived from it. Doubling and star steps may be implemented in the addition chain. This approach eliminates the computationally expensive step of generating the addition chain from an exponent, and therefore can greatly reduce the computation time of the modular exponentiation.

Exponentiation (or, in the groups employing additive notation, multiplication) is one of the most time-consuming operations of many public-key cryptographic protocols. One study of the SSL/TLS protocol estimated the performance hit of the RSA (Rivest Shamir Adleman) exponentiation to be between 20% and 60% of the total server running time.
Modular exponentiation (computing gx mod N) is very common and by far the most expensive operation of many cryptographic protocols. Traditional methods for fast exponentiation transform the binary exponent either implicitly or explicitly into an addition chain, which is used directly to perform exponentiation. However, it is computationally infeasible to generate optimal addition chains for large exponents. The traditional method of raising g to a random power x is to first generate random x and then apply the best available method for computing gx. However, this approach uses the inherently suboptimal step of generating the addition chain from an exponent.
There are many approaches to speeding up exponentiation in finite groups. The most general one is to treat g and x as inputs to the exponentiation algorithm, computing gx, and optimizing the algorithm's average (or worst case) running time. A different approach, called the fixed-base method, is applicable when g is fixed and thus the algorithm can take advantage of some precomputation that would be amortized over many invocations of the exponentiation algorithm. Yet another approach is to draw the exponent from a strategically chosen set that minimizes the expected running time of the exponentiation algorithm.
In view of the foregoing, there is a need for systems and methods that overcome such deficiencies. For example, it would be desirable to reduce the running time of exponentiation without increasing any memory requirement.

Systems and methods for generating random addition chains


Stochastic control problems of linear systems in high dimensions are solved by modeling a structured Markov Decision Process (MDP). A state space for the MDP is a polyhedron in a Euclidean space and one or more actions that are feasible in a state of the state space are linearly constrained with respect to the state. One or more approximations are built from above and from below to a value function for the state using representations that facilitate the computation of approximately optimal actions at any given state by linear programming.

1. Field of the Invention
The present invention relates generally to a method for solving stochastic control problems of linear systems in high dimensions.
2. Description of Related Art
(Note: This application references a number of different publications as indicated throughout the specification by reference numbers enclosed in brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found in the Section entitled "References" in the "Detailed Description of the Preferred Embodiment." Each of these publications is incorporated by reference herein.)
Computer-implemented Supply Chain Management (SCM) applications are designed to link a cohesive production and distribution network and thus allow an enterprise to track and streamline the flow of materials and data through the process of manufacturing and distribution to customers. SCM applications represent a significant evolution from previous enterprise resource planning (ERP) systems
One goal of SCM applications is to decrease inventory costs by matching production to demand. SCM applications utilize extremely complex forecasting and planning algorithms to predict demand based upon information stored in the enterprise's database. These applications also incorporate any changes in supply chain data into the forecast much faster than previous modes of calculation, allowing enterprises to more accurately predict demand patterns and schedule production accordingly.
Another goal of SCM applications is to reduce overall production costs by streamlining the flow of goods through the production process and improving information flow between the enterprise, its suppliers, and its distributors. Logistics-oriented systems, such as transportation, warehouse management, and factory scheduling applications, all contribute to reduced production costs. By ensuring real-time connectivity between the various parties in a supply chain, these applications decrease idle time, reduce the need to store inventory, and prevent bottlenecks in the production process.
Yet another goal of SCM applications is to improve customer satisfaction by offering increased speed and adaptability. SCM applications allow the enterprise to reduce lead times, increase quality, and offer greater customization, enhancing the customer relationship and improving retention.
SCM applications begin with forecasting and data mining applications analyzing information consolidated in the enterprise's database. Planning algorithms are used to generate a demand forecast upon which to base subsequent procurement orders and production schedules.
Nonetheless, there is a need in the art for improved planning techniques for SCM applications, especially where a SCM application models a Markov Decision Process (MDP), and the action space and the state space of the MDP model are continuous and related to each other through a system of linear constraints.

Method for solving stochastic control problems of linear systems in high dimension

International Business Machines Corporation


The liquid droplet ejection head includes: a nozzle which ejects a droplet of a liquid containing microparticles; a pressure chamber which connects with the nozzle; a piezoelectric element which varies a volume of the pressure chamber; a common liquid chamber which stores the liquid that is to be supplied to the pressure chamber; and a supply passage which connects the common liquid chamber to the pressure chamber, wherein the supply passage has a plurality of supply ports through which the common liquid chamber is connected to the supply passage, the supply ports being disposed in different positions in a direction of gravitational force.

1. Field of the Invention
The present invention relates to a liquid droplet ejection head and an image forming apparatus, and more particularly to a liquid droplet ejection head and an image forming apparatus which each eject a functional liquid containing dispersed microparticles.
2. Description of the Related Art
An inkjet printer (inkjet recording apparatus) is known as an image forming apparatus. An inkjet printer comprises an inkjet head (liquid droplet ejection head) in which a large number of nozzles (liquid droplet ejection ports) is arranged, and records an image or pattern on a recording medium by ejecting ink in the form of liquid droplets through the nozzles toward the recording medium while moving the inkjet head and the recording medium relatively to each other.
For example, an inkjet head of such an inkjet printer comprises a pressure chamber unit including: a pressure chamber which is supplied with ink from an ink tank via an ink supply passage (common liquid chamber); a piezoelectric element which is driven by electric signals corresponding to image data; a diaphragm constituting a part of the pressure chamber, which is deformed by driving the piezoelectric element; and a nozzle which communicates with the pressure chamber and ejects the ink in the pressure chamber in the form of liquid droplets when the volume of the pressure chamber decreases due to the deformation of the diaphragm. By combining dots formed by the ink that is ejected through the nozzles of the pressure generating units in the inkjet printer, an image or pattern is formed on a recording medium.
In recent years, inkjet printers have been used not only to form images by depositing a liquid such as ink on a sheet of recording paper, but also to form patterns and the like by ejecting a functional liquid containing dispersed microparticles. Embodiments of the microparticles that may be used include pigment, polymer resin, metal, glass, and oxides or compounds thereof.
When a raw material such as those described above is formed into microparticles and the microparticles are then dispersed and emulsified into a solvent liquid using a dispersing agent, the microparticles in the liquid aggregate and settle over time. If a functional liquid containing these aggregated and settled microparticles is ejected as is, unevenness occurs in the concentration or microparticle density of the liquid, leading to concentration unevenness or distortion in the ejection result and deterioration of the color reproducibility. As a result, it is difficult to maintain a high ejection result quality.
Under such circumstances, for example, Japanese Patent Application Publication No. 2003-72104 discloses an apparatus that maintains microparticles in a functional liquid in a consistently dispersed state. In the apparatus, a manifold (common liquid chamber) in which an ejection substance accumulates immediately before being ejected through a nozzle is provided in the interior of an ejection head. The manifold is provided with a stirring device such as a piezoelectric element, for example, and hence vibration is provided by the stirring device to the ejection substance in the manifold such that the ejection substance is stirred constantly.
As noted above, in a functional liquid containing dispersed microparticles, the microparticles in the liquid aggregate and settle over time. Particularly when the functional liquid is an adjusted ink in which a raw color material formed into microparticles is dispersed through a solvent liquid, the color material in the ink aggregates and settles over time such that the ink concentration is greater in a lower layer portion than an upper layer portion. When such ink is ejected by an ejection head structured such that the ink is supplied to a pressure chamber through a supply passage from the lower portion of a common liquid chamber, the thick ink that has settled near the bottom portion of the common liquid chamber is supplied first. As the ink is consumed by the print operation, the density of the image formed by the ejected ink gradually shifts from dark to light, and hence the image quality deteriorates.
In the apparatus disclosed in Japanese Patent Application Publication No. 2003-72104, in order to solve the problem described above by preventing the microparticles in the liquid from settling, the microparticles are maintained in a consistently dispersed state by providing the piezoelectric element as a device for stirring the ejection substance in the common liquid chamber (manifold) so that the ejection substance is subjected to vibration and stirred at all times. However, this stirring mechanism requires a drive circuit to drive the piezoelectric element, a control device to synchronize the stirring operation and ejection operation, and the like, leading to an increase in cost.

Liquid droplet ejection head and image forming apparatus


A vehicle hood includes a hood outer panel and a panel-shaped hood reinforcement which is arranged at the underside of the hood outer panel. The hood reinforcement includes an integral bend which extends in the vehicle width direction to allow the hood reinforcement to bend in the front to rear direction of the vehicle in a frontal crash. A bulge formed in the hood outer panel and the bend of the hood reinforcement are so arranged that the front end of the bulge and the bend substantially coincide with each other when viewed in plan.

(a) Field of the Invention
The present invention relates to a vehicle hood including a hood outer panel and a hood reinforcement arranged at the underside of the hood outer panel. In particular, it relates to an improvement in bending of the vehicle hood in a frontal crash.
(b) Description of Related Art
For improvements in safety of pedestrians and impact absorption of vehicles, there have been known vehicle hoods including a hood outer panel which is configured to bend surely at a predetermined position in a frontal crash.
Such vehicle hoods, however, have a problem. If the hood outer panel is formed with a bulge protruding upward beyond the other part of the hood outer panel for providing space for mounting engine auxiliaries, the hood outer panel is hindered from bending at a predetermined position in a frontal crash because the bulge is highly rigid than the other part and not easily deformed.
Accordingly, for example, Japanese Unexamined Patent Publication S59-176166 discloses forming the bulge as a separated part from the hood outer panel so that the bulge comes off the hood outer panel in a frontal crash.
Further, in conventional vehicle hoods, a lattice-formed frame (corresponding to a hood reinforcement) is provided at the underside of the hood outer panel. Since the lattice-formed frame is highly rigid at the lattice points, a pedestrian is greatly damaged if he/she is bumped against the lattice points. Accordingly, in response to the need for the protection of pedestrians in recent years, Japanese Unexamined Patent Publication No. 2003-191865 discloses a hood reinforcement which is panel-shaped to correspond to the shape of the hood outer panel.
However, since the former conventional vehicle hood includes the bulge separated from the hood outer panel, parts count increases, resulting in an increase in cost. If the bulge is integrally formed with the hood outer panel for design purposes, the bulge cannot come off the hood outer panel.
In the latter conventional vehicle hood, the state of bonding between the panel-shaped hood reinforcement and the hood outer panel becomes substantially uniform. This brings about dispersion of load of a frontal crash, and therefore the hood outer panel does not easily bend along a bend line at a predetermined position.
Moreover, if the hood outer panel and the hood reinforcement each have a convex form at the front ends thereof for design purposes when viewed in plan, the front end of the hood is reduced in rigidity. Therefore, in a frontal crash, the front end of the hood is deformed easily and the load of the crash is not smoothly transferred rearward. As a result, a bend line cannot be formed at a predetermined position.


A duplexed bus type network in which a main transmission line and a stand-by transmission line are interconnected by a repeater (30), a changeover switch (40) or a two-way amplifier, a modem at each station is duplexed and connected to the main transmission line and the stand-by transmission line, and, upon trouble in one modem (11A), only the relevant station is switched over to the modem (21A) belonging to the stand-by transmission line. When the main transmission line is broken, all the stations are simultaneously switched over to the stand-by transmission line.

Hitherto, LANs (local area networks) with a bus type structure using coaxial cables, such as CSMA/CD (IEEE 802.3) type LANs and token bus (IEEE 802.4) type LANs, have been widely used. Recently, bus type networks using optical fibers and optical star couplers as transmission media have been studied.
These bus type LANs are characterized, like a ring type LAN, by freedom from the possibility that turning off the power supply of a node station may exert an influence on the total system. The bus type LANs, however, have the drawback that the total system runs down or the system must be stopped when the transmission line is broken or at the time of providing an additional station. In the ring type LAN, on the other hand, duplexing the transmission line and providing a loopback function will prevent the system from running down upon breakage of the transmission line at one place.
Concerning a bus type network, therefore, attempts have been made to duplex the transmission line and modem portions so that normal operation of the system will be secured even upon breakage of the transmission line or failure in a modem.
FIG. 8 shows a conventional duplexed structure in a bus type LAN which employs coaxial cables. Modems 11A, 11B, 11C and modems 21A, 21B, 21C are connected to a main transmission line 10 and a stand-by transmission line 20 through branching devices 13 and 23 and node stations 3A, 3B and 3C can selectively connect themselves to either the main transmission line 10 or the stand-by transmission line 20 by their own switches 4B, 4B and 4C, respectively. Designated by numerals 12 and 22 are terminating resistors, each of which has an impedance equal to the characteristic impedance of the transmission line.
FIG. 9 shows a duplexed structure in a broadband bus type network. A main transmission line 10 and a stand-by transmission line 20 are terminated on one end side thereof respectively by terminating resistors 12 and 22, each having an impedance equal to the characteristic impedance of the transmission line. Head end remodulators 41 and 42 are provided at the other ends of the transmission lines, and two-way amplifiers 43 and 44 are provided at intermediate points of the transmission lines.
Normally, node stations 3A to 3C are connected to main modems 11A to 11C through switches 4A to 4C thereof and perform data transmission using the main transmission line 10. That is, in normal state, data output from a data terminal of one of the node stations 3A, 3B and 3C, for instance, the node station 3A is transmitted through the main modem 11A and the main transmission line 10 to the other node stations 3B and 3C.
In FIGS. 8 and 9, if a certain mode, e.g., 11A fails, the respective switches 4A, 4B and 4C at the stations are simultaneously set to the dotted line side to resume the data transmission through the modems 212A, 21B and 21C and the stand-by transmission line 20.
When the main transmission line 10 is broken, for instance, between the modem 11A and the modem 11B as indicated by the mark "X" in FIG. 8, the switches 4A to 4C are changed over to connect the stations 3A-3C to the stand-by modems 21A-21C, whereby data transmission can be performed by use of the stand-by transmission line 20.
FIG. 10 shows a duplexed bus type LAN using optical fibers and optical star couplers as transmission media. A main transmission line 10 and a stand-by transmission line 20 are constructed by use of optical fiber cables 10a, 20a and star couplers 10b, 20b, and duplexed by providing modems 11A, 11B, 11C and modems 21A, 21B, 21C. Switching between the main and the stand-by system is performed by switches 4A, 4B and 4C.
The switching is carried out in the same manner as in the bus type LANs of FIGS. 8 and 9, that is, in the following manner.
In normal state, data output from a data terminal of one of the node stations 3A, 3B and 3C, for example, the node 3A is sent through the main modem 11A into the main star coupler 10a. In the star coupler 10a, the data is output evenly to each port, to be transmitted to the other node stations 3B and 3C. If a certain mode, e.g., 11B fails, the respective switches 4A, 4B and 4C at the stations are simultaneously set to the dotted-line side, to resume data transmission through the star coupler 20b, cable 20a and optical modems 21A, 21B and 21C belonging to the stand-by system.
The above-mentioned duplexed system according to the prior art, however, has following problems:
(1) Because failure in only one modem (e.g., 11A) causes switching of the modems at all the stations of the main transmission line to the corresponding ones of the stand-by system, the operation of the entire system is not ensured and a very dangerous condition results. That is, because the modems operating in normal conditions at other stations 3B and 3C than the station 3A are also switched to the stand-by modems the operations of which are not guaranteed, the reliability of the total system is not always improved by the duplexing. This applies also to the broadband type bus network; PA1 (2) A failure occuring in a modem or a drop cable for a station does not affect information transmission among the other stations, so that it is rather difficult for all the stations to recognize the failure. Without recognition of the failure, switching to the stand-by system cannot be achieved. To obviate such a situation, special information for verifying the operating conditions of each station must be transmitted; PA1 (3) Even if a transmission system for solving the problem in (2) above is adopted, it is still difficult to discriminate breakage of a power supply for a station and a modem failure from each other. As a result, some limitations are imposed on the greatest merit of the bus type network, namely, the merit that "the power supply at any station can be turned on and off freely"; and PA1 (4) Even after the main transmission line is broken, data transmission may be possible between the stations (e.g., 3B and 3C in FIG. 8) which do not have the breakage point therebetween. On the other hand, data transmission is impossible between the stations (e.g., 3A and 3C) having the breakage point therebetween. In this case, it is difficult for each of the stations to judge whether the power supply of the other station is turned off or the transmission line is broken. Thus, it is difficult for each station to detect a breakage of the main transmission line, by simply observing the data transmission condition.
It is accordingly one object of the present invention to provide a highly reliable duplexed bus type network which is capable of switching (changing over) only a portion associated with trouble.
It is another object of the present invention to provide a highly reliable duplexed bus type network which can easily detect breakage of a main transmission line and can switch the transmission line upon the detection.

Duplexed bus type network with failure changeover


A set/operate mode switch is interposed between the door sensing or element door position activated switch and a remote monitoring station, to enable the remote station to monitor the door condition, or to enable a local signal assembly to monitor the door condition. The local signal assembly is made operative by the set/operate switch, so that the sensing element can be accurately set before turning door monitoring over to the remote station. While the local signal assembly is verifying the door condition, a shunt or shorting element keeps the remote monitoring station displaying a door open condition, all the while that the local signal assembly is operatively engaged, for security reasons. Only when the local signal assembly is isolated from the arrangement, can the remote monitoring station give a true signal of the door condition.

There are applications, especially in penal institutions, in which a door closure will have a sensing element, or door position activated switch, which can track the door condition: open or closed, and report the condition to a remote monitoring station for security reasons. At the remote monitoring station, the reported condition is signalled either audibly or optically. Such a sensing or door position activated switch is disclosed in U.S. Pat. No. 4,835,905.
Known products which have this feature can be compromised. The wires and connectors used to report the door condition can be connected improperly, by inadvertence or design, to report a door closed condition to the remote monitoring station when, in fact, the door is not closed, is not secured. To overcome this problem, it is conceivable to use two, separate switches. One would report to the remote station, and the other would report to wires at the door. However, in practice, it is extremely difficult or impossible to have the two switches aligned accurately enough to be used.
What has been long needed is a single controlling switch, used in combination with the sensing or door position activated switch, which can be operated to report the door condition to the remote station, while isolating a local signal assembly at the door, and can be operated to report the door condition, accurately, to such a local signal assembly, at the door. Ideally, operation of such a controlling switch would maintain a door-open signal, at the remote station, all the while that the local signal assembly is being operated to set or establish the correct functioning of the door sensing element in the door closure.


The output voltage of a cathode drive-type semiconductor laser driving circuit is set to a minimum, power consumption by a driving circuit portion is suppressed, and the heat that is generated by the optical head or the optical disc device is reduced. In addition to a conventional configuration, the semiconductor laser driving circuit of the invention measures the cathode voltage (Vout) of a semiconductor laser (1) and controls the anode voltage (Vld) such that the cathode voltage (Vout) becomes a predetermined level, and by doing so sets the output voltage of the semiconductor laser driving circuit to a predetermined level in order to curtail power consumption by the driving circuit and minimize the rise in temperature of the optical head or the optical disc device.

In recent years, blue high-output semiconductor lasers have been developed, and high-density recording technology for optical discs that uses this short-wavelength laser light has been developed and adopted for practical use. In principal, blue semiconductor lasers have a larger forward voltage than do conventional red semiconductor lasers, and thus for a given forward voltage consume more power and produce more heat. For this reason, when a blue semiconductor laser is mounted to an optical head, there is a large rise in temperature due to the generation of heat, and thus the reduction of power in other blocks in the optical head and improvements in heat radiation have become important issues.
Conventionally, one method that has been used to reduce power consumption by the semiconductor laser driving circuit that is used in an optical disc device is the method of, in MD devices for music playback only, for example, to directly connect the semiconductor laser and the DC-DC converter to one another and then apply feedback based on the monitor results of the laser output of the semiconductor laser. With this method, the series voltage drop between the semiconductor laser and the DC-DC converter is a minimum, and moreover, in the DC-DC converter there is little voltage drop loss like in voltage regulators, and thus this method is ideal from the perspective of reducing power consumption. However, one issue with this method is that the response speed when switching from playback to record is not sufficient, and thus as it is, the method is not suited for recording devices.
The semiconductor laser driving circuit of Patent Document 1 is an example where the response speed is improved. Patent Document 1 discloses an "anode drive" type semiconductor laser driving circuit that performs control of the semiconductor laser by controlling the current that flows to the anode of the semiconductor laser, whose cathode is grounded. The forward voltage of the semiconductor laser (hereinafter, "Vop"; it should be noted that here this is equal to the anode voltage) varies by semiconductor laser and changes depending on the value of the forward current (If) of the semiconductor laser, and thus when Vop is equal to or less than a predetermined value, the voltage that is applied to the semiconductor laser driving circuit may be lowered by lowering the output voltage of the DC-DC converter, thereby suppressing unnecessary power consumption. In other words, if the Vop is equal to or less than a predetermined value, a semiconductor laser driving circuit that is low power and that switches between the record power and the playback power at high speed by switching the output voltage of the DC-DC converter to a low voltage that has been determined in advance is achieved.
Patent Document 2 discloses an anode drive-type semiconductor laser driving circuit whose aim is to reduce power consumption. In the semiconductor laser driving circuit of Patent Document 2, to accurately measure the circuit voltage, the output voltage of the DC-DC converter and the Vop are each measured through a level shift circuit and a peak hold circuit, and the difference between these two is calculated to measure the voltage that is applied to the semiconductor laser driving circuit, and the output voltage of the DC-DC converter is controlled based on this result.
Patent Document 3 discloses an anode drive-type semiconductor laser driving circuit. In the semiconductor laser driving circuit of Patent Document 3, the Vop of a blue semiconductor laser is measured through a peak hold circuit or an integrating circuit, for example, and the output voltage of the DC-DC converter is controlled so that a voltage that is equal to the voltage obtained by adding the voltage necessary for the semiconductor laser driving circuit to the Vop is output.
Patent Document 1: JP 2000-244052A
Patent Document 2: JP 2002-158395A
Patent Document 3: JP 2002-260266A

Semiconductor laser driving circuit, and optical disc device and integrated circuit provided with semiconductor laser driving circuit


The vehicle steering control device comprises a steering control member actuatable by the driver and a slaving device comprising two sensors each supplying a detection signal representative, respectively, of the angular position of the vehicle's steerable wheels and of the position of the control member, a motor for pivoting the steerable wheels in response to a control signal, and a slaving circuit producing this control signal in response to the detection signals. The steering control device further comprises a coupling member able to mechanically connect the steering control member to the steerable wheels when the slaving device is not working properly whereby, in such an event, the driver retains control over his vehicle's steering.

As most vehicles of this kind have two steerable wheels, and sometimes even more, reference will only be made in the following description to "the steerable wheels" so as not unduly to clutter up the description. But it will readily be seen that the present invention applies without change to vehicles having only one steerable wheel.
The driver of such a vehicle is obviously provided with a steering control member that he can actuate to cause the steerable wheels of his vehicle to pivot in relation to their pivotal axes, and hence to steer the vehicle. In most cases this member consists of a steering wheel which the driver can rotate about an axis. In other cases, this member consists not of a steering wheel but, for example, of a hand-actuated stick that the driver of the vehicle can move, parallel to itself or by causing it to pivot about an axis, in a plane which is, for example, perpendicular to the longitudinal axis of the vehicle.
In most vehicles of the above-defined kind, the slaving of the angular position of the steerable wheels to the position of the steering control member is performed by a purely mechanical device.
It has already been proposed to produce such slaving by means of a device having an electric or electronic slaving circuit that controls a motor mechanically linked to the steerable wheels in response to electric signals that are respectively representative of the pivotal angle of these wheels and of the position of the steering control member, these signals being supplied to the circuit by position sensors that are mechanically linked to said wheels and to said member, respectively.
In the remainder of this description, such a device will be termed "electric slaving device" and the electric or electronic circuit it comprises will be termed "slaving circuit".
In a steering control device using such an electric slaving device, there is no mechanical link between the vehicle's steerable wheels and its steering control member.
It should be noted that, throughout the present description, the term "mechanical link" between a first element and a second element, here the steerable wheels on the one hand and the steering control member on the other hand, must be understood to mean a functional link entirely made up of mechanical components and whereby any movement by one of the elements results in a corresponding movement by the other element, and not to mean the link that merely results from the fact that these two elements form part of the same vehicle.
A vehicle steering control device having an electric slaving device suffers from the major drawback of depriving the vehicle's driver of all control over the steering of the vehicle in case of faulty operation of the electric slaving device, the term faulty operation obviously applying also to a complete breakdown of the device. Such faulty operation of the electric slaving device could for instance be caused by a substantial drop, or by the complete fading out, of its supply voltage or by a failure of one of the components of the slaving circuit or of one of the position sensors.
An object of the present invention is to propose a vehicle steering control device which does not suffer from the drawback of the above-described known device, i.e. a device that enables the vehicle's driver to retain control of the steering of the vehicle even in the case of faulty operation of the electric slaving device.


An adhesive for hard tissue bonding which has a sufficient pot life and excellent biocompatibility and is replaced with bone over time, and an adhesive kit for hard tissue bonding are provided. In addition, bone cement is provided which has excellent biocompatibility and is replaced with bone over time. An adhesive for hard tissue bonding includes: a cyanoacrylate monomer; and beta-tricalcium phosphate or hydroxyapatite. An adhesive kit for hard tissue bonding includes: a liquid agent containing a cyanoacrylate monomer; and a powdery agent containing beta-tricalcium phosphate or hydroxyapatite. Bone cement includes: a cyanoacrylate polymer; and beta-tricalcium phosphate or hydroxyapatite.

In recent years, the estimated number of patients with osteoarthritis and osteoporosis among locomotive syndromes that an aging society has increased year by year to 54.7 million people. Furthermore, the annual number of patients requiring artificial joint replacement is 66,000 cases of gonarthrocace, 47,000 cases of coxarthrosis, and 55,000 cases of femoral prosthesis (refer to Yano Research Institute Ltd., 2015, 6th Scientific Commission Medical Device Expert Committee).
Examples of bone cement with which bones, joints, and the like are filled for treatment of the above-described diseases in the related art include ones (for example, refer to PTL 1) which have a synthetic resin as a main component and contain radiopaque materials such as barium sulfate, tantalum, and tungsten for making bone cement impermeable to X-rays.
On the other hand, a 2-cyanoacrylate adhesive is conventionally known as an instant adhesive and has excellent adhesiveness. In addition, a 2-cyanoacrylate adhesive has been used as an adhesive for bonding soft tissue of the esophagus, the stomach, the intestinal tract, the digestive tract, blood vessels, the trachea, and anastomosis of bronchi (refer to, for example, PTL 2).

Adhesive for hard tissue bonding, adhesive kit for hard tissue bonding, and bone cement


Described is a circuit for receiving a differential input signal at two substantially symmetrically built up current paths and for providing an output signal therefrom. At least one current path comprises means for adjusting the timing information of the input signal to the timing information of the output signal. The adjustment can be accomplished by modifying a voltage level in the respective current path until the timing information of the output signals at least substantially represents the timing information of the input signal, e.g. by modifying an impedance or a current in the respective current path. The adjusting of the timing information is executed by applying a defined input signal with a known timing information, comparing the timing information of the resulting output signal with the timing information of the input signal, and modifying at least one voltage level in at least one of the current paths until the timing information of the output and input signals at least substantially match.

The present invention generally relates to differential digital circuits and the timing behavior thereof.
Digital circuits are normally operated in a two-level, or binary, mode. This means that at a steady state, each input and output is in one of two conditions. These conditions (or states) are often referred to as true or false states, high (V.sub.h) or low (V.sub.l) levels, or `1` or `0` states, respectively. Because circuit outputs are generally voltages, these two states are characterized by two voltage ranges based on a higher voltage V.sub.ih and a lower voltage V.sub.il, where V.sub.ih >V.sub.il. The voltages V.sub.ih and V.sub.il are also called the high and low logic thresholds. It is agreed that--as shown in FIG. 1--if a nodal voltage V satisfies the inequality V>V.sub.ih, then the node is in a high state, and if V<V.sub.il, the node is in a low state.
For some applications, the two-level mode has been proved insufficient, and instead thereof, a differential logic is applied. In digital circuits using the differential logic (also referred hereafter as differential digital circuits, or simply differential circuits), the signal voltage is defined as the difference between two node voltages V=V.sub.p -V.sub.n. For the logic state of V, the conditions as described for the two-level mode apply. In a steady state, the two node voltages V.sub.p and V.sub.n of the differential logic always have opposite states, i.e. if V.sub.p >V.sub.ih then V.sub.n <V.sub.il, and vice versa. Among other advantages, circuits applying differential logic generally exhibit constant power supply current, a comparably low voltage swing and thus high speed, low susceptibility to noise and comparably low noise generation.
Differential circuits, including the differential digital circuits, have formerly been implemented in bipolar technologies such as in ECL (emitter-coupled logic) circuits. ECL is often used in computers that require high speed. To achieve such high speeds, ECL consumes a large amount of electric power, requiring expensive cooling. Current trends in the electronic industry towards higher integration and smaller systems also force an application of differential circuits in MOS (metal oxide semiconductor) technologies. The main differences between bipolar and MOS transistors, used to implement differential circuits, are the following. A single IC chip cannot be packed with as many transistors in ECL as in MOS. If too many transistors are placed on an ECL chip, it becomes damaged by the excessive heat. MOS chips consume very little power if the signals do not change with a very high frequency; therefore, a large number of transistors can be packed onto a single chip. Further more, MOS transistors show higher threshold voltages and a lower transconductance at comparable speed and power supply currents.
FIG. 2 shows an inverter circuit as an example for a differential digital circuit. A current source 10 feeds a first current path 20 and a second current path 30. The first current path 20 comprises a first current switch 40 and a first load 50, and the second current path 30 comprises a second current switch 60 and a second load 70. The first 40 and second 60 current switches are normally embodied by transistor elements, such as bipolar or MOS transistors, and receive at their control electrodes differential input signals IN.sub.p and IN.sub.n, respectively. The first 50 and second 70 load may also be embodied by transistor elements, such as MOS transistors, or by other resistor means as known in the art. Each one of the current paths 20 and 30 respectively provides a differential output signal OUT.sub.p or OUT.sub.n at a node between the current switches and the load.
In operation, the higher signal of the differential input signals IN.sub.p and IN.sub.n switches on the respective one of the current switches 40 or 60, so that the potential of the output signal (OUT.sub.p or OUT.sub.n) in that current path will be drawn from a higher to a lower potential. Accordingly, the lower signal of the differential signals IN.sub.p and IN.sub.n switches off the other one of the current switches 40 or 60, so that the potential of the output signal in that current path will be drawn from a lower to a higher potential. The circuit of FIG. 2 thus inverts the differential input signals IN.sub.p and IN.sub.n.
It is clear that the function of the circuit in FIG. 2 can be modified by exchanging the input signals or the output signals resulting in a non-inverting buffer.
In general, a state transition is a change of a node voltage from a first state to a second state, where in a digital circuit the state transition normally is between two defined states. FIG. 3 shows an example for such a state transition. The time while a voltage is in a range between the threshold voltages V.sub.ih and V.sub.il is called the transition time t.sub.tr. For physical reasons the transition time must be non zero, t.sub.tr >0.
The point in time when a voltage reaches V=(V.sub.ih +V.sub.il)/2 is generally referred to as a timing mark of the transition. For differential signals, the timing mark is the point in time, when the differential signals are equal. In FIG. 3, the transition starts at a time t.sub.1 and ends at a time t.sub.3, whereby at a time t.sub.2 the two differential signals are equal and reach the voltage (V.sub.ih +V.sub.il)/2. The transition time is defined as t.sub.tr =t.sub.3 -t.sub.1. The transition mark of that transition is at t.sub.2.
Timing information is transmitted or processed when signals change from one state to another and generally comprises information about timing marks. A digital circuit, which is processing or transmitting timing information, generates a sequence of output state transitions as a result of a sequence of input state transitions. Output state transitions occur at times t.sub.o (1), t.sub.o (2) . . . t.sub.o (N) caused by input state transitions that occur at times t.sub.i (1), t.sub.i (2) . . . t.sub.i (N), as depicted in FIG. 4a.
The relationship between timing information of input transitions must be reflected at the output of the system. Further more, the time elapsing between input state changes should also elapse between output state changes caused by their respective input state changes. Otherwise the system has changed the timing information which should be avoided in most applications. Thus, a digital circuit generates accurate timing, if the following equation for the transition times is satisfied: EQU t.sub.o (k+1)-t.sub.o (k)=t.sub.i (k+1)-t.sub.i (k), where k is an integer.(eq.1)
The time difference between a timing mark t.sub.i (k) of a transition at an input of a system or device, and a timing mark t.sub.o (k) of a thereto corresponding output transition is called the propagation delay t.sub.pd (k), with t.sub.pd (k)=t.sub.o (k)-t.sub.i (k). For an ideal digital circuit, the propagation delay is a constant value with t.sub.pd (k)=t.sub.pd (k+n) where n is an integer. However, in real digital circuits the propagation delay t.sub.pd (k) might differ depending on the actual input state, the frequency of state changes at the input, and so forth.
In particular when digital electronic circuits are used for time measuring, e.g. in testing applications for testing e.g. integrated circuits (IC's) or other electronic devices, it is crucial for the operation that the circuits provide an accurate timing, i.e., the variation of the propagation delay t.sub.pd (k) should be small with respect to the transition time of the signal to be measured, transmitted or otherwise processed.
The propagation delay t.sub.pd (k) of a differential circuit is commonly defined as the time elapsing between corresponding time marks, i.e the point in time when V.sub.i =0 or V.sub.ip =V.sub.in and the point in time when V.sub.o =0 or V.sub.op =V.sub.on, as depicted in FIG. 4b. This is in accordance with the time elapsing between the transition timings as described above.
Miniaturization of electrical circuits is generally envisaged since miniaturization means not only that a higher integration of the circuits can be achieved, but also that higher frequencies can be applied due to the smaller feature sizes. However, with an increased integration and miniaturization of differential circuits, it has been found that the timing behavior, such as the propagation delay t.sub.pd (k), significantly starts to vary, even between identical differential circuits. Further more, it was detected that e.g. the propagation delay t.sub.pd (k) turns out to diverge and not to be a constant value for a specific circuit, so that the timing information will be changed by that circuit. This leads to timing defects which are completely unacceptable for most applications, and in particular, for timing sensitive applications such as in testing applications.
Specifically since differential circuits are mainly used for high precision applications, the effect of an unpredictable timing behavior has been found as an enormous drawback for that technology. However, a reason for that variation in timing behavior could not have been sufficiently given in the art, so that the circuit designers had to either accept only a certain degree of integration and miniaturization, or to use different technologies.

Differential circuits with adjustable propagation timing