A semiconductor structure is disclosed. The semiconductor structure includes a polycrystal substrate, a first single crystal layer formed thereon and a second single crystal layer formed on the first single crystal layer. A variation of coefficients of thermal expansion (CTE) between the first single crystal layer and the polycrystal substrate is less than 25%. There is no lattice mismatch between the first single crystal layer and the polycrystal substrate.

1. Field of the Invention
The invention relates to a semiconductor structure, and more particularly to a composite polycrystal substrate for growth of a single crystal layer.
2. Description of the Related Art
Recently, there has been enormous interest in the growth of Group III nitrides, and particularly gallium nitride (GaN) thin films, Jpn. J. Appl. Phys. Vol. 34 (1995) pp. L 797-L 799. GaN, and related (Aluminum, Indium) N alloys are being utilized for the production of efficient optoelectronic devices, such as, light emitters and detectors spanning the spectral range of visible to deep ultra-violet (UV) light. The direct, wide bandgap and the chemical stability of Group III nitrides are very beneficial for high-temperature and high-power electronic devices, such as, hetero-junction bipolar and field effect transistors.
When GaN is directly grown on a sapphire substrate, the growth mode is three-dimensional due to the large lattice mismatch, the chemical dissimilarity, and the thermal expansion difference. The layer contains structural defects such as point defects, misfit dislocations, and stacking faults. These defects degrade the structural, morphological, and electronic properties of the film. In order to achieve high quality epitaxial growth, researchers have introduced a thin low-temperature grown AlN or GaN layer serving as a buffer layer. This layer provides nucleation sites for subsequent two-dimensional GaN growth at higher temperatures, see H. Amano, M. Kito, K. Hiramatsu, and I. Akasaki, Jpn. J. Appl. Phys. 28, L2112 (1989) and S. Nakamura, T. Mukai, M. Senoh, and N. Isawa, Jpn. J. Appl. Phys. 31, L139 (1992). Thus, control of buffer layer growth is the most important step in improving GaN layer properties. The effect of buffer layer thickness and growth temperature on GaN layer properties has been researched by G. S. Sudhir, Y. Peyrot, J. Kruger, Y. Kim, R. Klockenbrink, C. Kisielowski, M. D. Rubin and E. R. Weber, Mat. Res. Symp. Proc. 482, pp. 525-530 (1998); Y. Kim, R. Klockenbrink, C. Kisielowski, J. Kruger, D. Corlatan, Sudhir G. S., Y. Peyrot, Y. Cho, M. Rubin, and E. R. Weber, Mat. Res. Symp. Proc. 482, pp. 217-222 (1998); J. Kruger, Sudhir G. S., D. Corlatan, Y. Cho, Y. Kim, R. Klockenbrink, S. Rouvimov, Z. Liliental-Weber, C. Kisielowski, M. Rubin and E. R. Weber, and results published in Mat. Res. Symp. Proc. 482 pp. 447-452 (1998). Buffer layers for Group-III nitride growth has been discussed in Mohammad et al., "Progress and Prospects of Group-III Nitride Semiconductors", Prog. Quant. Electr. 1996, Vol. 20, No. 5/6 pp. 418-419, hereby incorporated by reference in its entirety. Various buffer materials are disclosed.
GaN and related alloys are of particular interest for light emitting thin films because of their ability to cover a wide spectral range. Because a crystalline substrate with a lattice parameter near that of GaN is not yet available, different growth techniques are desirable in order to limit defect density.

Industrial Technology Research Institute


A dehumidifying system supplies a gas free of organic substances. The dehumidifying system includes a holding case, and a rotor rotatably held in the holding case and bearing an adsorbent. The interior of the holding case is divided into an adsorbing zone and a regenerating zone by partition plates attached to the holding case. A process gas is supplied into the adsorbing zone. The process gas processed in the adsorbing zone is supplied into an objective space. A regenerating gas is supplied into the regenerating zone to eliminate moisture and organic substances adsorbed by the adsorbent in the adsorbing zone from the adsorbent.

A semiconductor device fabricating process for fabricating highly integrated semiconductor devices is required to use a gas not containing gaseous impurities and having a dew point of −50° C. or below. A dry dehumidifying device using a rotor provided with an adsorbent is used widely for producing clean, dry gas having such a low dew point.
A dehumidifying device for producing dry air having a low dew point is disclosed in, for example, JP 63-50047 B. The device is provided with a cylindrical honeycomb rotor formed by winding a single-sided corrugated board around an axis of rotation and having many parallel gas passages. The single-sided corrugated board is formed by processing a special paper sheet containing activated carbon and a ceramic material as principal components. Process gas passages, regenerating gas passages and virgin gas passages are formed separately around the axis of rotation. The process gas is passed through the rotating honeycomb rotor to dehumidify the process gas. Moisture removed from the process gas is carried away by the regenerating gas. This dry dehumidifying system has an adsorbent produced by fixing lithium chloride in pores of the activated carbon.
A dry dehumidifying system for producing dry air having a low dew point disclosed in JP 11-188224 A uses lithium chloride, silica gel or zeolite as an adsorbent.
A rotor of the dry dehumidifying device will be explained. The rotor is held rotatably in a case. A rotor and a case disclosed in JP 2001-276552 A will be described by way of example. Referring to FIGS. 11 and 12, a dry dehumidifying device 100 includes a case 110 provided with radial partition plates 111, and a rotor 101 rotatably held in the case 110. The rotor 101 is divided temporarily into parts by the partition plates 111 in an adsorbing zone S, a cooling zone T and a regenerating zone U as the rotor 101 rotates. Process air flows into the part of the rotor 101 in the adsorbing zone S through one of the opposite end surfaces of the rotor 101, for example, a front end surface on the front surface of the paper shown in FIG. 11.
The rotor 101 is formed by shaping a honeycomb base sheet 104 and has, for example, eight sectors 102 having a sectorial cross section and bearing an adsorbent. The sectors 102 are joined together in a cylindrical structure. The sectors 102 are reinforced by metal spokes 103. A metal rim 107 is put on the cylindrical structure formed by joining the sectors 102. As shown in an enlarged view in FIG. 13, each sector 102, the metal spoke 103 and the rim 107 are joined together or adhesively bonded together with a caulking material 120, such as heat-resistant silicone.
In the adsorbing zone S, moisture contained in the process air is adsorbed by the adsorbent borne by the rotor 101. Clean, dry air leaves the rotor 101 through the other end surface, namely, a front end surface on the back surface of the paper in FIG. 11, of the rotor 101. In the regenerating zone U, hot air heated at temperatures between about 180 and about 200° C. flows through the back end surface of the rotor 101 and flows through the rotor 101 to evaporate and carry away moisture adsorbed by the rotor 101 in the adsorbing zone S. The rotor 101 is exposed to hot air of a high temperature and is heated. If the hot rotor 101 moves through the adsorbing zone S, the process air cannot be dehumidified and the process air passed through the rotor 101 has a high dew point. Therefore, the cooling zone T is interposed between the regenerating zone U and the adsorbing zone S to cool the rotor 101.
Sealing members formed by laminating a PTFE film to a fluororubber sheet are attached to the partition plates 111 demarcating the adsorbing zone S, the regenerating zone U and the cooling zone T. The sealing members are pressed slidably against the end surfaces of the rotor 101 to prevent the leakage of the process air and the mixing of the process air and the hot air.
The dehumidifying device 100 has a limited dew point lowering ability. Usually, two dehumidifying devices are cascaded as mentioned in JP 63-50047 B. The two dehumidifying devices are connected such that the process air passed through an adsorbing zone in one of the two dehumidifying devices flows into an adsorbing zone in the other dehumidifying device. A dehumidifying system disclosed in JP 11-188224 A has three cascaded dehumidifying devices for further dew point lowering.
The semiconductor device fabricating process uses various chemicals, and produces a large variety of organic compounds including those of molecules having large diameters, those of molecules having small diameters, those having low boiling points and those having high boiling points.
Although the known dehumidifying devices are capable of satisfactorily adsorbing moisture, they are not satisfactory in organic compound adsorbing capacity. Thus, organic compounds contained in the process air could not be satisfactorily adsorbed by the known dehumidifying devices and some part of the organic compounds contained in the process gas is carried away by the process air leaving the dehumidifying device.
Accordingly, it is a first object of the present invention to remove both moisture and organic compounds.
Moreover, the semiconductor device fabricating process produces a large amount of gaseous, high-boiling organic compounds, such as DMSO (dimethyl sulfoxide), MEA (monoethanol amine) and HMDS (hexamethylenedisilazane). Although the known dry dehumidifying devices are able to adsorb those high-boiling organic compounds, the adsorbent of the dry dehumidifying device adsorbing those high-boiling organic compounds cannot be regenerated, because the adsorbent needs to be heated at a temperature on the order of 300° C. to remove the adsorbed high-boiling organic compounds from the adsorbent and the adsorbent is unable to withstand such a high temperature. For example, the highest temperature that can be withstood by activated carbon is on the order of 140° C. It is possible that activated carbon ignites if activated carbon is exposed to high-temperature air of temperatures exceeding 300° C. Therefore, activated carbon cannot be used. Silica gel cannot be used because the ability of silica gel deteriorates if silica gel is exposed to high-temperature air of temperatures exceeding 300° C. Hot air of very high temperatures exceeding 300° C. must be used to remove the high-boiling organic compounds in the regenerating zone U.
The caulking material 120, such as heat-resistant silicone, is unable to withstand high temperatures exceeding 200° C. The bonding ability or adhesive strength of the caulking material 120 caulking gaps between the metal spokes 103 and the sectors 102 deteriorates when high-temperature air of 300° C. or above flows through the rotor 101. Consequently, the sectors 102 fall off the rotor 101 and, in some cases, the rotor 101 becomes unserviceable. Since high-temperature air cannot be passed through the rotor 101, high-boiling organic compounds are continuously accumulated in the rotor 101 and the adsorbing ability of the adsorbent decreases accordingly.
Since the temperature of air that flows through the regenerating zone U of the rotor 101 is limited, the accumulated high-boiling organic compounds cannot satisfactorily be removed, the cleaning and dehumidifying abilities of the rotor 101 decrease and hence the rotor 101 needs to be replaced inevitably with a new one. A regenerating method of regenerating the deteriorated rotor 101 washes the rotor 101 with water. However, this regenerating method is unable to remove organic substances, particularly, high-boiling organic substances satisfactorily, and is unable to restore the rotor 101 to its initial ability. Water used for washing the rotor 101 needs to be treated by a waste water treatment, which is very expensive.
Accordingly, it is a second object of the present invention to provide a dehumidifying system using an adsorbent that can be regenerated by heat of a high temperature on the order of 300° C. after adsorbing high-boiling organic compounds.

Dehumidification system and dehumidification method


This invention relates to cyclic diamides that are readily polymerized to form poly(terephthalamides). The resulting poly(terephthalamides) have high crystallinity, high temperature capabilities, dimensional stability, low moisture sensitivity, and solvent and chemical resistance.

1. Field of the Invention
The present invention relates to monomers of high temperature polyamides. Particularly, the present invention relates to cyclic terephthaldiamides that polymerize to form poly(terephthalamides).
2. Description of the Prior Art
The chemistry of polymerization of cyclic monomers or oligomers is well known in the polymer art. Such cyclic monomer polymerization processes have been utilized in polyamide applications, particularly for reaction injection molding (RIM) applications. Typically, in such a polymerization application, an anhydrous lactam (cyclic amide) is in-situ polymerized at or above 100.degree. C. in the presence of one or more of basic catalysts such as alkali and alkaline earth metals, their hydrides, hydroxides, alkoxides, oxides, alkyls or amides. Various lactams having 6-12 carbon atoms, such as caprolactam, pyrrolidone, piperidone, valerolactam and lauryllactam, have been known to be useful for in-situ polymerization processes. The advantage of the in-situ polymerization processes of lactam monomers, such as RIM, is based on the fact that the monomers employed are low melting and the polymers resulting therefrom are high melting and highly crystalline, and the polymerization process does not produce any byproducts. In addition, lactam monomers have low melt viscosity, obviating the need to utilize high pressure equipments necessary in conventional melt-injection molding processes.
Although the polyamides resulting from the above-mentioned process exhibit a range of valuable properties, they have disadvantages in that they are dimensionally unstable, because of their inherent hygroscopic property, and have limited high-temperature capabilities. Therefore, it is desirable to provide monomers or oligomers of polyamides that can be in-situ polymerized and have improved dimensional stability and high-temperature capability.
The polyamides derived from terephthalic acid and alkanediamines, which are commonly referred in the art as poly(terephthalamides), have been known in the art to exhibit high melting point and low moisture sensitivity. However, the high melting point of poly(terephthalamides), which is higher than 300.degree. C. and practically coincides with the thermal decomposition temperature of the polyamides, renders the production of the polymers by the conventional melt polymerization process unpracticable. Various publications have disclosed various methods of overcoming this polymerization difficulty. For example, U.S. Pat. No. 2,752,328 to Magat; U.S. Pat. No. 3,382,216 to Blaschke et al.; and U.S. Pat. No. 3,696,074 to Tsuda et al. disclose terephthalamide copolymer compositions having a lower crystalline morphology than homopolymer terephthalamides. Although such terephthalamide copolymers are melt. processible, they do not retain the benefits of crystalline polymers such as solvent resistance and various high temperature utilities including high heat deflection temperature. Therefore, it is desirable to produce poly(terephthalamides) of high crystallinity that have high temperature capabilities, dimensional stabilities and low moisture sensitivity, and to provide monomers of such poly(terephthalamides) that can be polymerized without utilizing the conventional polymerization processes which may thermally decompose the resulting poly(terephthalamides).
Stetter et al. disclosed in their article, "On Understanding Macrocyclic Ring System", Chem. Berichte, 91, 1775-1781 (1958), a range of macrocyclic diamides from aromatic dicarboxylic acids including 2,5-diaza-1,6-dioxo-[6](1,2)-orthocyclophane; 2,7-diaza-1,8-dioxo-[8](1,2)-orthocyclophane; 2,9-diaza-1,10-dioxo-[10](1,2)-orthocyclophane; 2,7-diaza-1,8-dioxo-[8](1,3)-metacyclophane; 2,9-diaza 1,10-dioxo-[10](1,3)-metacyclophane; 2,9-diaza-1,10-dioxo-[10](1,4)-paracyclophane; 2,11-diaza-1,12-dioxo-[12](1,4)-paracyclophane; 2,13-diaza-1,14-dioxo-[14](1,4)-paracyclophane; 1,1'-diaza-2,2'-dioxo-[2,2](1,2)-orthocyclophane; and 3,3'-diaza-4,4'-dioxo-[6,6](1,4)-paracyclophane. Of these cyclophanes, 2,11-diaza-1,12-dioxo-[12](1,4)-paracyclophane and 2,13-diaza-1,14-dioxo-[14](1,4)-paracyclophane exhibit molecular configurations that may polymerize. However, Stetter et al. did not recognize any use for the macrocyclic diamides they had synthesized.

Preparation of polyamide from arylene cyclic diamide


A valve assembly for a water circulation system includes a valve body defining a bypass passage between a hot water side and a cold water side of the valve body. The bypass passage has a valve seat therein. A bypass valve is received within the bypass passage. The bypass valve restricts the flow of water through the bypass passage based on a temperature of the water in the bypass passage. The bypass valve is variably positionable with respect to the valve seat to control a bypass shut-off temperature of the water.

The subject matter herein relates generally to water circulating systems, and more particularly, to valve assemblies for water circulating systems.
Home and industrial water distribution systems distribute water to various fixtures, including sinks, bathtubs, showers, dishwashers and washing machines, that are located throughout the house or industrial building. The typical water distribution system brings water in from an external source, such as a city main water line or a private water well, to the internal water distribution piping system. The water from the external source is typically either at a cold or cool temperature. One segment of the piping system takes this incoming cold water and distributes it to the various cold water connections located at the fixtures where it will be used (e.g., the cold water side of the faucet at the kitchen sink). Another segment of the piping system delivers the incoming cold water to a water heater which heats the water to the desired temperature and distributes it to the various hot water connections where it will be used (e.g., the hot water side of the kitchen faucet). At the fixture, cold and hot water either flows through separate hot and cold water control valves that are independently operated to control the temperature of the water into the fixture by controlling the flow rate of water from the separate valves, or the water is mixed at a single valve that selectively controls the desired water temperature flowing from the fixture.
A problem with most home and industrial water distribution systems is that hot water is not always readily available at the hot water side of the fixture when it is desired. This problem is particularly acute in water use fixtures that are located a distance from the hot water heater or in systems with poorly insulated pipes. When the hot water side of these fixtures is left closed for some time, such as overnight, the hot water in the hot water segment of the piping system sits in the pipes and cools. As a result, the temperature of the water between the hot water heater and the fixture lowers until it becomes cold or at least tepid. When opened again, it is not at all uncommon for the hot water side of such a fixture to supply cold water through the hot water valve when it is first opened and for some time thereafter. At the sink, bathtub or shower fixture located away from the water heater, the person desiring to use the fixture will either have to use cold or tepid water instead of hot water or wait for the distribution system to supply hot water through the open hot water valve. Most users have learned that to obtain the desired hot water, the hot water valve must be opened and left open for some time so that the cool water in the hot water side of the piping system will flow out ahead of the hot water. For certain fixtures, such as virtually all dishwashers and washing machines (which are not usually provided with a bypass valve), there typically is no method of "draining" away the cold or tepid water in the hot water pipes prior to utilizing the water in the fixture.
The inability to have hot water at the hot water side of the fixture when it is desired creates a number of problems. One problem is having to utilize cold or tepid water when hot water is desired. This is a particular problem for the dishwasher and washing machine fixtures in that hot water is often desired for improved operation of those appliances. Certain dirty dishes and clothes are much easier to clean in hot water as opposed to cold or tepid water. Even in those fixtures where the person can let the cold or tepid water flow out of the fixture until it reaches the desired warm or hot temperature, there are certain problems associated with such a solution. One such problem is the waste of water that flows out of the fixture through the drain and, typically, to the sewage system. This good and clean water is wasted (resulting in unnecessary water treatment after flowing through the sewage system). Water waste is compounded when the person is inattentive and hot water begins flowing down the drain and to the sewage system. Yet another problem associated with the inability to have hot water at the hot water valve when needed is the waste of time for the person who must wait for the water to reach the desired temperature.
The use of bypass valves and/or water recirculation systems in home or industrial water distribution systems to overcome the problems described above have been known for some time. However, these water recirculation systems have problems and limitations. For example, these water recirculation systems are typically operated by a pump and the pump must be operated for a certain cycle time to dispel all of the cooled water from the hot water pipe system before hot water is available at the fixture. Problems arise when hot water is desired at the fixture before the end of a cycle, or when the pump is not running. However, constantly running the pump so that hot water is always available is not economical. Accordingly, the above mentioned problems (e.g. waste of water) are still prevalent in water recirculation systems today.
An additional problem with known bypass valves is that over time and with age the valves, particularly valves that are directly operated by a thermal actuator (such as a wax filled cartridge) tend not to have any toggle action. Instead, after a number of on-off cycles, the valves tend to just throttle the flow until the water reaches an equilibrium temperature, at which time the valve stays slightly cracked open. While this meets the function of keeping the water at a remote fixture hot, leaving the valve in a slightly open condition does present two problems. First, the lack of toggle action can result in scale build-up on the actuator body and/or rod because the rod is constantly extended. At least some known bypass valves utilize screens to filter debris or minerals from the bypass passage. However, these screens tend to clog themselves, limiting the flow to the bypass passage. Second, the open valve constantly bleeds a small amount of hot or almost hot water into the cold water piping, thereby keeping the faucet end of the cold water pipe substantially warm. If truly cold water is desired (i.e., for brushing teeth, drinking, or making cold beverages), then some water must be wasted from the cold water faucet to drain out the warm water. It is also detrimental to have any noticeable crossover flow (siphoning) from hot to cold or cold to hot with any combination of faucet positions, water temperatures, or pump operation.

This patent is subject to a terminal disclaimer.

Water circulation system valve assemblies having water temperature control


A power plug with overloaded display providing users with a function of a warning display for protecting the power plug from over-heated melting and from shorting and catching on fire. The plug includes an embedded positioned block arranged on a periphery of electric metal-pins of the power plug, and a thermochromic film is coated on the surface of the embedded positioned block, and warning characters are printed on the embedded positioned block. The external body of the power plug is made by injection modeling with mixed transparent PVC and thermochromic materials, or the embedded positioned block may be directly injected with thermochromic materials, or connected with a detecting transistor linked by a light emitting diode (LED). When the power plug is over-heated and the temperature of the power plug generally increases, the thermochromic materials or the LED will display a warning message.

Generally, electric equipment using alternating current usually is plugged into an alternating current plug by a power plug through wires. As we know, alternating current power source generally is divided into 2 types, 110 voltage and 220 voltage. At present, the most common structure applied for power plug comprises 2 or 3 electric metal-pins (hot, neutral, and ground), wherein one end of the electric metal-pins is connected with the copper core of wires, after connecting, the back section of the electric metal-pins and a predetermined length of wire are molded or injection modeled with PVC to form an external body of the power plug, and the external body is suitable for being held by hand. The external body comprises a flexible rear fin, and enables the front section of the electric metal-pins exposed outside the power plug to contact the electric metal-sheet for conducting electricity, in this way, a power plug made of PVC is completed.
As we know, the electric metal-pin of a power plug generally is the easiest part to accumulate heat when using, especially the part between electric metal-pins and core of the wires usually is the key place for shorts and fires. If the equipment is overloaded, the temperature will increase.
Therefore, the PVC of the conventional used power plug, which contacts the electric metal-pins, will be hardened after a period time of using because of heat, resulting in the position changing between the two electric metal-pins or deforming the power plug. When in an abnormal overload condition and the temperature in electric metal-pins is increasing, if users do not shut down the power in time and check the equipment, which will melt the PVC and result in high temperature sparks. These conditions will make electric wires or equipment catch fire more easily, even resulting in fire accidents.
Then, if the conventional power plug can display a warning function when abnormal temperature increases, accidents will be avoided at an early stage.


A method of controlling the movement of copy sheets along a copy sheet path by providing a target by a high level controller for the movement of copy sheets within the copy sheet path and controlling movement of copy sheets within segments of the copy sheet path. Movement in each segment is controlled by subcontrollers activating segment drives. Feedback data are conveyed to the high level controller and to other subcontrollers on the movement of copy sheets within segments of the copy sheet path and copy sheet movement is adjusted by the copy sheet drives of selected segments of the copy sheet path in order to achieve the target.

The goal of a paper path system in a typical xerographic printing system is to transport media from a feeding unit in synchronism with a moving image bearing photoreceptor surface. The media necessarily must arrive at the transfer zone at a given time and with a given velocity to match the velocity of the image bearing photoreceptor surface. Traditional media handling systems have relied on the use of expensive and precisely manufactured actuators (such as roller transports) for moving media such as paper and transparencies with very little or no feedback control involved. These systems typically do not perform very well when subjected to handling a wide range of media as well as exhibit problems with maintaining accuracy and reliability at high speeds. The present invention uses a more control-centric design of media handling systems that takes advantage of the diamatic decrease in chip cost and moves away from parts requiring high tolerance. It does so by embedding more controls in the system and trimming the overall cost by reducing the cost of hardware. The invention also enables significantly better performance by being able to handle a wider range of media at higher speeds through effective use of modern control strategies. Also prior art systems are often open loop systems with the media running at a specific speed and position adjustment being made at a transfer registration station just prior to transfer. A difficulty with such systems is the often erratic and abrupt adjustments that must be made at the registration station due to the unpredictability of photoreceptor and media drives and the uncertainty of the position of the image on the photoreceptor. With little time and space for adjustment, the correction can be erratic. This is particularly true in higher speed, higher volume machines.
It is known in the prior art, for example, U.S. Pat. Nos. 5,328,168 and 5,257,070 to selectively activate copy sheet drives after a machine jam in order to position copy sheets for favorable jam clearance including the steps of maintaining a predetermined interdocument space between copy sheets and systematically purging copy sheets from zones of the paper path in a predetermined order. A difficulty with these prior art systems, however, is the restriction of the systems to jam recovery. It would be desirable, therefore, to provide a relatively smooth and more accurate adjustment technique over the entire paper path to synchronize the arrival of copy sheets and images on a photoreceptor at an image transfer station.
It is an object of the present invention, therefore, to provide a multi-layered hybrid hierarchical control architecture for media handling. It is another object of the present invention to provide a combination of modular, discrete and continuous controllers that interact with copy sheets as the copy sheets move along a paper path. It is still another object of the present invention to provide a discrete controller to plan distance-time trajectories for media on a media path and to provide continuous controllers for keeping the media on the respective trajectories using multi-layered architecture. Further advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Hybrid hierarchical control architecture for media handling


The present invention provides Fast Initial Link Setup communication device and method, wherein, the device comprises: a service processing module which generates a Beacon frame which physical frame header comprises a first identification information field and/or a physical layer convergence procedure service data unit comprises a second identification information field, and the value of the first identification information field is a first value and/or the value of the second identification information field is a second value, which shows that a Fast Initial Link Setup function is supported, and sends the Beacon frame; and/or receives an initial link setup first message; and a wireless transceiver module. The present invention solves the compatibility problem that an STA that does not support the FILS function enters a WLAN network which supports the FILS function and an STA that supports the FILS function enters a WLAN that does not support the FILS function.

A new project group 11ai is established in the IEEE (Institute of Electrical and Electronics Engineers) 802.11, and the main object of this project group is to achieve simultaneous setup of fast initial link between many STAs (station, terminal/station point) and an AP (Access Point) in a wireless local area network when the STAs enter the coverage area of the AP, and the need of the putting forward the project group is to set up initial link between 100 STAs and the AP in one second.
A current process of initial link between the STA and the AP totally comprises about 13 steps, as specifically shown in FIG. 1. The current initial link setup manner cannot meet the needs of the 11ai, thus should be changed. Being different from a current AP, an AP supporting an FILS (Fast Initial Link Setup) function can set up initial link with an STA supporting the FILS function in a new faster mode.
In this way, a problem will be rendered that, if an STA which does not support the FILS function enters a WLAN (Wireless Local Area Network) network supporting the FILS function, if the process of setting up the initial link follows the FILS function mode, the STA which does not support the FILS function cannot analyze a network access instruction issued by the AP in the WLAN supporting the FILS function, and vice versa, an STA supporting the FILS function cannot set up fast initial link with an AP that does not support the FILS function in the FILS manner.
Therefore, a new technical solution is desired to solve the network incompatibility problem that an STA cannot be connected with an AP in the WLAN when an STA that does not support the FILS function enters a WLAN network which supports the FILS function and an STA that supports the FILS function enters a WLAN that does not support the FILS function.

Fast initial link setup communication device and method

Yulong Computer Telecommunication Scientific (Shenzhen) Co., Ltd.


An apparatus for temporarily blocking fluid flow through a pipe comprises a housing configured to enclose a portion of a pipe and a flow blockage device. The housing includes a first part defining a housing chamber for receiving the pipe, and a second part defining a stowage space adjacent the housing chamber. The flow blockage device is movable through an aperture formed in one side of the pipe to an installed position in the housing chamber. The flow blockage device includes an outer sealing part that is configurable between an unexpanded configuration allowing the flow blockage device to pass through the aperture and allowing fluid flow through the pipe and an expanded configuration configured to block fluid flow through pipe by substantially preventing passage of fluid between outer side surfaces of the flow blockage device and inner surfaces of the pipe.

A variety of techniques are known in the art for creating a temporary blockage in a pressurized pipe conveying fluid to allow repair or upgrading of the pipe (e.g., to allow a control mechanism such as an isolation valve or thermostatically controlled valve to be inserted downstream of the temporary blockage).
Traditionally, the process of introducing a temporary blockage has been by virtue of freezing the pipe to form an ice "plug" to block flow through the pipe. However, this technique is not suited to pipes conveying fluids such as oil or gas and only offers a limited period of blockage before the ice plug melts with the potential for disastrous failure if the ice plug gives way. Furthermore, the pipe must generally be cold to form the plug, thereby requiring heating systems in need of repair to cool before the plug can be formed.
A variety of solutions have been conceived to solve the problem, including the arrangements disclosed in GB 2344396, U.S. Pat. No. 3,532,113, U.S. Pat. No. 5,316,037, U.S. Pat. No. 3,687,166 and WO 2011/012899. All of these documents disclose arrangements incorporating a "pipe cutting tool and valve" all-in-one solution in which the cutting device is left in place along with the valve installed in the pipe. As will be appreciated, this can add to the cost of the device and result in a valve that is larger than desired.

Apparatus for blocking fluid flow through pipes


The invention relates to a method for producing 1-methyl-3-nitroguanidine. According to said method, nitroguanidine is reacted with methylamine and/or a methylammonium salt in an aqueous solution, at temperatures of 30 to 60xc2x0 C. and at a pH value of 95 to 12.3. In this way, yields of 1-methyl-3-nitroguanidine of at least 80% and degrees of purity greater than 99% can be obtained in a particularly environmentally friendly and technically simple way.

The present invention relates to a method for producing 1-methyl-3-nitroguanidine which is an important intermediate product for the production of biologically active compounds, in particular insecticides (cf. xe2x80x9cNicotinoid Insecticides and the Nicotinic Acetylcholine Receptorxe2x80x9d, I. Yamamoto, J. E. Casida (ed.), Springer Verlag, Tokyo, 1999).
A series of proposals has already been made in the prior art regarding the production of 1-methyl-3-nitroguanidine. One known method of production is the dehydration of methyl guanidine nitrate with the help of sulfuric acid (cf. J. Amer. Chem. Soc., 1933, pp. 55, 731). The corresponding methyl guanidine nitrate is, according to U.S. Pat. No. 2,425,341, available from an aqueous cyanamide solution and methylammonium nitrate, however the method is unsatisfactory due to the relative minor yield and the necessary post-purification.
According to the method variant described in WO 98/43 951 methyl guanidine nitrate is obtained by reacting methylammonium nitrate with water-free cyanamide in organic solvents, such as ether or alcohols, and thereafter is reacted directly into 1-methyl-3-nitroguanidine. The use of water-free cyanamide is not, however, economical as compared to aqueous cyanamide solutions.
It is furthermore known that 1-methyl-3-nitroguanidine can be obtained by nitration of methyl guanidine sulfates (cf. J. Amer. Chem. Soc., 1933, pp. 55, 731). This method of production also has the disadvantage of a unsatisfactory yield as well as a relative large amount of waste water.
The reaction of methylammonium nitrate with calcium cyanamide or dicyandiamide (cf. Can. J. Chem., 1958, 36, 737) also leads to unsatisfactory results since the purity of the methyl guanidine nitrate obtained by this means is less than 90%.
A further method for the production of 1-methyl-3-nitroguanidine is that methylisothiourea sulfate is first nitrated and thereafter the methylmercapto group is substituted by a methyl amino residue (cf. J. Amer. Chem. Soc., 1954, 76, 1877). The splitting of methyl mercaptan, especially when performing the method on a large industrial scale, causes considerable operational problems.
Moreover it is known that 1-methyl-3-nitroguanidine can be obtained in that a greatly alkaline nitroguanidine solution is reacted at 60xc2x0 C. with a large excess of methylammonium chloride (cf. J. Amer. Chem. Soc., 1947, 69, 3028 and J. Chem. Soc. 1957, 70). With this process, the purity of the final products which must be purified in complicated methods, and in particular the individual yields attained of pure product of between 43 and 66% are very unsatisfactory. Very large amounts of urea or guanidine derivates results as by-products with a development of gaseous N2O. Moreover large amounts of waste water also result.
The direct reaction of aqueous methyl amine solutions with nitroguanidine at temperatures of  greater than 60xc2x0 C. (cf J. Amer. Chem. Soc., 1927, pp. 49, 2304, and Proc. Am. Acad. Arts Sci., 1926, pp. 61, 437) results with only insufficient yields of 36 to 45% in 1-methyl-3-nitroguanidine.
The same disadvantages are also shown by the direct reaction described in EP-A 798 293 of a methylamine solution with nitroguanidine at 0-40xc2x0 C. The desired final product is obtained also with this manner of procedure with only a maximum yield of 60%. The method is moreover very uneconomical due to the long reaction times of about 24 hours and the high dilution which leads, with the insufficient yields of space/time, to very large amounts of waste water.
Representation of the Invention
The present invention was therefore based on the object to develop a method for the production of 1-methyl-3-nitroguanidine which does not have the disadvantage of the prior art, but that allows the desired final product to be acquired with at good yields and high purity in an especially environmentally sound manner and by a technically simple means.
This object was solved according to the invention in that nitroguanidine was reacted with methylamine and/or a methylammonium salt in an aqueous solution at temperatures of 30 to 60xc2x0 C. and at a pH value of 9.5 to 12.3. It was surprisingly found that the formation of N2O was also considerably reduced along with an increase in yields, by means of which the danger of formation of explosive mixtures with the ammoniac formed as a by-product is considerably reduced.
Thus nitroguanidine with methylamine and/or a methyl ammonium salt is reacted in methods according to the invention in an aqueous solution at temperatures of 30 to 60xc2x0 C., in particular 40 to 45xc2x0 C.
The salts of strong mineral acids, such as e.g. the sulfate, hydrochloride, nitrate or phosphate, are used as methylammonium salts.
It is to be considered essential to the invention that the pH value is adjusted during the reaction to a value of 9.5 to 12.3. Surprisingly, it was found that the yields obtainable depend to a great extent on the pH value during the reaction. When the method according to the prior art was reproduced, it was found that pH values of 13.0 to 14.0 occur thereby which always lie above the pKa value of nitroguanidine (12.4). With such reaction conditions, yields of clearly above 60% cannot be obtained due to the side reactions. If the reaction is performed on the other hand at a pH value below the pKa value of nitroguanidine, yields amounting to 80 to 95% are obtained. pH values of 11.0 to 12.0 during the reaction have proven to be especially advantageous here. The yields are again reduced if the pH values lie clearly below 9.5.
The adjustment of the pH value takes place either by the addition of the methyl amine and the methylammonium salt in such a molar ratio that the desired pH value adjusts itself, or by the usual use of strong bases or acids. A mineral acid, selected from the group sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, is used preferably as the strong acids, while, for example, sodium hydroxide solution or potassium hydroxide solution are used as strong bases. According to a preferred embodiment, the methylamine and/or the methylammonium salt are used in such an amount that the molar amount of the sum of the two components, based on the nitroguanidine used, corresponds to an excess of 5 to 50 mol-%.
Principally, a higher excess of methylamine and/or methylammonium salt with up to 100% can be used without a substantial formation of the dialkylated product 1,2-dimethyl-3-nitroguanidine being observed thereby. A higher increase than the preferred 5 to 50% by weight of methylamine and/or methylammonium salt, however, decreases the economicability of the method according to the invention.
After the reaction is concluded, which is ended as a rule after 2 to 3 hours, the final product is separated, preferably by filtration. A neutralization of the reaction mixture before the filtration is also possible without this acting negatively in any form on the yield. Optionally, the final product can be subsequently rinsed with some cold water and dried.
The advantages of the method according to the invention consist essentially in that 1-methyl-3-nitroguanidine can be obtained with yields of at least 80% und purities greater than 99% in a manner especially friendly to the environment and technically simple, which is why this method is suited especially for large industrial use.

Method for producing 1-methyl-3-nitroguanidine


The invention relates to an adjustment method, especially for adjusting optical or fiber optical components. According to an embodiment of the invention, a first adjustment process is carried out in which, after a cooling process, the regions of the actuator in which the tensile stresses or compressive strains are frozen following the cooling process are brought to a critical temperature in relation to the operational temperature range of the actuator, at least until the flow processes of the material at said critical temperature are largely completed. A second adjustment process is then carried out.

The invention concerns an adjustment method, particularly for adjusting optical or fiber optical components, with the features of the preamble of patent claim 1. Moreover, the invention concerns an actuator which is suitable for the same and an optical component.
Laser adjustment methods and actuators suitable for the same have been developed in recent times to enable extremely precise adjustment, e.g., of micromechanical components.
The basic principle of laser adjustment consists of heating a predetermined region of an actuator using a high-energy, preferably pulsed laser beam in a short time, in which the thermal expansion of the relevant region is blocked by corresponding further regions of the actuator. In this manner, compression strains build up in this heated region, which result in a plastic deformation of this region upon reaching the yield point. When this region is cooled down after the high-energy laser beam is switched off, the thermal shrinkage of this region is again essentially prevented by the further regions of the actuator. This leads to the build-up of tensile stresses in the previously heated region which lead to a defined deformation of the actuator, in which the adjustment of a component joined to the actuator is enabled in this process.
The basic principle of such an adjustment method is illustrated in FIG. 1. FIG. 1a shows the starting state of a bar 3 made of a suitable material which is restrained between two rigid demarcations 1. At the starting temperature, e.g., room temperature (20° C.), the bar 3 has a length l0. The center region 3a of the bar 3 is heated by a laser beam 5 in a short time.
This results in the first place in compressive strains σ(−) in the bar 3 since the thermal longitudinal expansion of the bar 3 is blocked by the rigid demarcations 1. In this phase, a negative expansion ε is also customarily defined which corresponds to the compressive strains formed in the bar 3. This phase of the adjustment method is illustrated in FIG. 1b.
If the compressive strains σ(−) exceed the temperature-dependent yield point σF, a plastic deformation of the bar 3 arises in the region 3a. Correspondingly, the compressive strains in the bar 3 are reduced. This situation is illustrated in FIG. 1c.
After the laser beam 5 is switched off, the region 3a of the bar 3 begins to cool off, causing a thermal shrinkage of the bar 3. In this process, tensile stresses σ(+) arise in the bar 3 which in actual practice frequently lie in the vicinity of the temperature-dependent yield point σF(T). This situation is represented symbolically in FIG. 1d because seen in the longitudinal direction of the bar 3 whose ends are joined by means of spring elements 7 to the rigid demarcations 1 . . . . [Note: incomplete sentence in the German original]. The spring forces corresponding to the tensile stresses σ(+) cause a defined deformation of the actuator in a practically realized actuator. In this connection, FIG. 1d also shows that the tensile stresses σ(+) arise through the shortening of the bar 3 due to the plastic deformation in the region 3a caused during the heating, in which the length of the bar l1 after the adjustment procedure at the starting temperature is smaller than the original length l0 at the starting temperature.
A problem in the previously known adjustment methods consists in that, as was previously mentioned, the tensile stresses frozen in the bar 3 lie relatively close to the yield point σF. The same can apply also to the compressive strains which occur in those regions which block the thermal expansion or rather the thermal shrinkage of the bar. Since micromechanical or optical components or rather subassemblies in actual practice are always specified for a certain temperature range, e.g., a range from −40° C. to +80° C., and must fulfill predetermined requirements for accuracy and long-term stability within the specified range, there results in previously known adjustment methods a maladjustment of the actuator if the adjusted components or rather the subassembly is brought to a temperature in the upper region of the specified range and the original adjustment was carried out at a significantly lower temperature, such as room temperature. This effect is caused by the temperature dependency of the yield point σF, most materials which are suitable for the manufacture of actuators for laser adjustment methods having a yield point which decreases with increasing temperature. If a temperature is reached at which the yield point σF falls below the value of the frozen-in tensile stresses, this results in a flowing of the material and in a reduction of the tensile stresses to the value of the yield point σF at the relevant temperature. Naturally, this is associated with a corresponding maladjustment of the actuator which is not acceptable at least for components requiring extremely precise adjustment which must be specified over a wide temperature range.

Adjustment method, particularly a laser adjustment method, and an actuator suitable for the same


The invention relates to a method of creation of three-dimensional alignment patterns that includes providing a layer of optically recordable and polarization sensitive material having a thickness that is greater than, or equal to, a predefined thickness, and concurrently illuminating the optically recordable medium with two coherent beam of same or different polarization with predetermined angle between the beams such that the said beams impinge from the same side or from the opposite sides upon the layer of the recordable material. The invention further relates to polarization volume holograms based on the said alignment patterns and polarization holographic element including a single layer or a stack of several layers of optically recordable materials containing single or multiple polarization volume holograms.

Polarization volume gratings and optical elements based on them have gained increasing interest for applications in optics, such as beam steering devices, waveguides, and display technologies.
Conventionally, polarization volume gratings were made by patterned alignment of liquid crystals (LC) or reactive mesogens (RM) as their polymerizable version using a photoalignment layer. In this case, the photoalignment layer includes elongated anisotropically absorbing molecular units (small molecules or fragments of polymeric molecules) arranged in a particular periodic pattern usually produced by holographic technique, and liquid crystal is deposited on the photoalignment layer so that the liquid crystal molecules are aligned along the local alignment direction of said molecular units in photoaligning layer. However, when the photoalignment layer is used, liquid crystals can be arranged in only certain three-dimensional configurations (e.g., only along the plane defined by the photoalignment layer). Furthermore, the preparation of these elements includes many technical steps and thus, is rather complicated.

Methods for three-dimensional arrangement of anisotropic molecules, patterned anisotropic films, and optical elements therewith


A fuel cell system that employs a two-position valve at the cathode exhaust gas output for controlling the pressure within the fuel cell stack to control the stack relative humidity. In one embodiment, the two-position valve is switchable between a fully open and a fully closed position, where the valve is opened when the fuel cell system is operating at a low operation temperature and the valve is closed when the fuel cell system is operating at a high operation temperature. A fixed restriction valve is provided in parallel with the two-position valve so that when the two-position valve is fully closed, the proper amount of pressure is provided at the cathode output. In another embodiment, the two-position valve employs sized leak paths so that when the two-position valve is in the closed position, the cathode exhaust gas can still flow through.

1. Field of the Invention
This invention relates generally to a fuel cell system employing back-pressure control and, more particularly, to a fuel cell system that employs a discrete two-position valve at the cathode exhaust of the system fuel cell stack to control stack pressure and relative humidity.
2. Discussion of the Related Art
Hydrogen is a very attractive fuel because it is clean and can be used to efficiently produce electricity in a fuel cell. The automotive industry expends significant resources in the development of hydrogen fuel cells as a source of power for vehicles. Such vehicles would be more efficient and generate fewer emissions than today's vehicles employing internal combustion engines.
A hydrogen fuel cell is an electrochemical device that includes an anode and a cathode with an electrolyte therebetween. The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen gas is disassociated in the anode to generate free hydrogen protons and electrons. The hydrogen protons pass through the electrolyte to the cathode. The hydrogen protons react with the oxygen and the electrons in the cathode to generate water. The electrodes from the anode cannot pass through the electrolyte, and thus are directed through a load to perform work before being sent to the cathode. The work acts to operate the vehicle.
Proton exchange membrane fuel cells (PEMFC) are a popular fuel cell for vehicles. The PEMFC generally includes a solid polymer electrolyte proton conducting membrane, such as a perflurosulfonic acid membrane. The anode and cathode typically include finely divided catalytic particles, usually platinum (Pt), supported on carbon particles and mixed with an ionomer. The combination of the anode, cathode and membrane define a membrane electrode assembly (MEA). MEAs are relatively expensive to manufacture and require certain conditions for effective operation. These conditions include proper water management and humidification, and control of catalyst poisoning constituents, such as carbon monoxide (CO).
Fuel cells are typically combined in a fuel cell stack to generate the desired power. The fuel cell stack receives the cathode input gas as a flow of air, typically forced through the stack by a compressor. Not all of the oxygen in the air is consumed by the stack and some of the air is output as a cathode exhaust gas that may include water as a by-product.
The humidity or wetness of the membranes in a fuel cell stack is an important design criteria for effective stack operation. Too much water within the stack acts to prevent the oxygen in the cathode input gas from reaching the catalyst on the cathodes. Too little water within the stack causes the stack membranes to dry out and become more susceptible to cracking and other damage. The more current that the stack generates, the more water is generated as a by-product of the electrochemical process. However, the more air that is forced through the stack by the compressor to provide more current, the more the stack membranes dry out. Typically, the stack has a 110% relative humidity during its most efficient operation. For 110% relative humidity, the exhaust gas is saturated 100%, and also includes a little bit of excess water.
Another factor that affects the stack relative humidity is stack temperature. As the stack temperature increases, the stack's ability to hold water in the vapor state also increases making it more difficult to maintain a desired stack relative humidity because more water is required to do so. Another factor that affects stack relative humidity is the stack pressure. As the pressure in the stack increases, the ability of the stack to hold water in the vapor state decreases. Thus, one of the most commonly used techniques to control cathode relative humidity is to control the fuel cell system pressure and temperature.
Fuel cell systems must reject waste heat. A fuel cell system will include a thermal coolant sub-system that removes heat from the stack so that it operates at its desired operating temperature. The heated coolant from the stack is directed to a radiator that reduces the temperature of the coolant so that it can be returned to the stack to remove the stack waste heat. The size of the radiator limits how much heat can be removed from the coolant.
The amount of waste heat that the coolant sub-system can reject is directly proportional to the operating temperature of the fuel cell system. If the system is able to operate at a higher temperature, a smaller radiator can be employed to remove the heat, thus conserving space. Unfortunately, a higher operating temperature requires a higher system pressure to keep the stack relative humidity at the desired level. In other words, as the temperature of the stack rises, its ability to hold water increases, thus requiring more water to meet the desired relative humidity. The higher pressure cancels the effect of the higher temperature on relative humidity. At higher operating temperatures, however, the stack may not produce enough water to meet the required relative humidity.
Because the size of the radiator is limited in a vehicle, a fuel cell system typically must operate at higher temperatures. Therefore, it becomes necessary to increase the pressure of the fuel cell stack so that more water is held therein to meet the desired relative humidity. However, high cathode pressures require larger amounts of compressor power, which results in a reduction in system efficiency.
Two approaches are known in the art to control fuel cell system pressure. One known approach is to employ a fixed orifice at the cathode exhaust output. Particularly, for high temperature applications the cathode output orifice is sized to provide a sufficient back-pressure to meet the relative humidity requirements at a maximum system temperature. However, the output orifice also causes high system pressure at low output power, and thus, the fuel cell system efficiency will suffer because of the higher compressor parasitic power.
For low temperature applications, where the thermal sub-system size is not critical, the cathode output orifice is sized to provide a nearly zero pressure drop. This allows the fuel cell system to run with low compressor parasitic losses, and is therefore efficient over the entire operating range. However, this fuel cell system will be large as a result of the large radiator required to reject the low-grade heat.
Modeling results have shown that a fixed orifice is capable of reducing the flow and pressure of the cathode exhaust gas without overloading the thermal sub-system. As a fuel cell power module decreases in flow and power, the amount of the waste heat the radiator has to dissipate will decrease. The amount of waste heat a radiator can dissipate is proportional to the temperature difference between the coolant and the ambient air. This value is often represented by Q/ITD, where Q is the waste heat and ITD is the initial temperature difference between the coolant and the air. Radiators are sized for a maximum Q/ITD at maximum power. Therefore, as the fuel cell turns down in flow and power, the waste heat requirement is lowered, which allows the operating temperature to be lowered. This allows the operating pressure to be lowered.
FIG. 1 is a graph with cathode input air flow on the horizontal axis and the required compressor pressure on the vertical axis showing the possible compressor delivery pressure for a fuel cell system employing only a fixed orifice to control system pressure. Graph line 40 shows the operation curve of the system for flow versus pressure for a high pressure drop at the fixed orifice, and graph line 42 shows the operation curve for flow versus pressure for a near zero pressure drop at the fixed output orifice. The fuel cell system will operate on one of the graph lines 40 or 42, regardless of the system operating temperature. The high pressure graph line 40 wastes energy at part power conditions, and the low pressure graph line 42 can only meet humidity requirements at low temperatures.
Another known approach is to use active cathode pressure control. This has been done in the past with high-resolution control valves. These high-resolution control valves offer many discrete valve open positions or an analog control where fluid flow through the valve can be set at any desirable location. The position of the valve is determined by the current operating temperature of the system and the amount of water that is being generated by the stack to provide a calculation of what pressure is necessary to provide a 110% stack relative humidity. Further, it is necessary to provide a safety device that prevents the valve from failing in the closed position, which could cause catastrophic stack failure from high pressure. While this approach offers a good solution that attempts to optimize system efficiency over its entire operating range, the control valve and support software are high cost components. Further, in the majority of the operating conditions of a fuel cell system, this level of control is unnecessary.
FIG. 2 is a graph with cathode input air flow on the horizontal axis and the required compressor pressure on the vertical axis showing the possible compressor delivery pressures for a fuel cell system employing a high resolution back-pressure valve. Graph line 44 shows how the cathode pressure can be directly controlled independent of flow to provide the desired relative humidity. At a constant low temperature operation, the control valve is wide open so that the pressure drop at the cathode exhaust is near zero. As the flow increases, the system temperature increases, and the valve will be systematically closed to provide the desired fuel cell back-pressure to control the relative humidity.
For fuel cell systems having a high resolution back-pressure control valve, the valve position is changed as a function of coolant temperature in order to maintain the desired relative humidity. However, the pressure drop across a fixed orifice is a function of the fluid velocity, fluid viscosity and orifice shape. Because the orifice shape cannot be changed, the cathode pressure and flow rate cannot be independently controlled. If the fixed orifice is sized to meet the humidity requirements at the maximum temperature, maximum flow and maximum Q/ITD point, it will provide sufficient humidity control in turn down. The minimum pressure required to maintain the desired humidity is given by operating at the minimum temperature possible, while maintaining a maximum Q/ITD condition in turn down. This required pressure is less than the pressure provided by the pressure drop across a fixed orifice in turn down when sized at the maximum point.
A system model was constructed where the maximum allowable Q/ITD was set at maximum power and flow. As the module turned down in flow and power, the coolant temperature was lowered only as much as possible without exceeding the maximum Q/ITD. The system back-pressure requirement was then calculated in order to meet the required humidity level. This gives a flow versus pressure drop curve that is required of the back-pressure valve in order not to exceed the maximum Q/ITD limit. FIG. 3 is a graph with cathode input air flow on the horizontal axis and back-pressure valve pressure drop on the vertical axis, where graph line 46 shows this relationship.
The model was re-run using a fixed area orifice for back-pressure control. The orifice was modeled based on a sharp edge orifice that was sized to meet the desired humidity at the maximum flow and temperature condition. The pressure drop through a sharp edge orifice is proportional to the square of the fluid velocity. Under this assumption, a flow versus pressure drop curve was generated for the system using the fixed area orifice, as shown by graph line 48 in FIG. 3. This modeling shows that the pressure drop for the fixed area orifice meets or exceeds the pressure drop requirements to achieve the desired humidity at steady state turn down points. The fixed area orifice will cause the fuel cell to be slightly over pressurized at part power conditions, which will give a slightly higher than optimal humidity. This will cause a slight system efficiency hit, but is not damaging to stack durability. If the fixed orifice pressure drop was less than the pressure drop required to meet the Q/ITD limit, then the humidity would be lower than desired and the stack may be damaged.

Fuel cell system back-pressure control with a discrete valve


A display integrated type position reading apparatus includes a display device driven for display in accordance with a driving signal in synchronization with a predetermined clock signal, and a conductive tablet mounted on a display screen of the display device. In operation, a CPU controls a tablet controller to apply voltage to the tablet. In response to a depression of an arbitrary position on the main surface of the tablet, the CPU reads out the depressed position as a digital signal via an A/D converter. The sampling by the A/D converter relating to reading is carried out at sampling points so as to avoid the mixing of noise, caused by a signal for driving the display unit, into the digital signal, resulting in an improvement in the read out accuracy of the depressed position.

1. Field of the Invention
The present invention relates to a display integrated type position reading apparatus, and more particularly, to improvement of position reading accuracy in reading out a specified position on a thin film and displaying it on a screen in an apparatus having a transparent thin film resistor mounted integrally on a display screen such as a liquid crystal plate.
2. Description of the Background Art
FIGS. 7 and 8 show structures of a display integrated type tablet apparatus employed in a conventional apparatus and in an embodiment of the present invention. Referring to FIG. 7, a display integrated type tablet apparatus includes a CPU (Central Processing Unit) 1 for centralized management and control of the apparatus, a ROM 2 and a RAM 3 for storing programs and data, a clock 4, an I/O (Input/Output) unit 5 including a printer and a CRT (Cathode Ray Tube) connected to the apparatus, a keyboard 6 provided for entering external data, a display controller 12 controlled by the CPU 1, an A/D converter (analog/digital converting circuit) 8, a tablet controller 9, a tablet 10 controlled by the controller 9, and a display device 11 formed of a liquid crystal plate driven by the display controller 12 for display. The liquid crystal plate includes a plurality of liquid crystal elements arranged in a matrix. Each element is driven by the controller 12 for screen display.
FIG. 8 shows the structure of the tablet 10 and the display device 11. The tablet 10 is formed of a structure where an X direction transparent film resistor 10a which is a transparent thin film resistor having an electrode provided at both ends (depicted as a thick line in the drawing) of the horizontal direction in the drawing (referred to as the X direction hereinafter) and a Y direction transparent film resistor 10b which is a thin film resistor having an electrode provided at both ends (depicted as a thick line in the drawing) of the vertical direction in the drawing (referred to as the Y direction hereinafter) are overlaid with a very small uniform gap therebetween. The display screen of the display device 11 is positioned at the side of the film resistor 10b opposite to the film resistor 10a. The X direction transparent film resistor 10a has the current flow from the X.sub.H side electrode towards the X.sub.L side electrode at the time of voltage application by the controller 9. The Y direction transparent film resistor 10b has the current flow from the Y.sub.H side electrode towards the Y.sub.L side electrode at the time of voltage application by the controller 9. It is assumed that voltage is applied to film resistors 10a and 10b by the controller 9. When a user depresses the surface of the tablet 10 with the tip of a pen or a pencil, the film resistor 10a is brought into contact with the film resistor 10b at that depressed position, whereby the depressed position is detected by a voltage signal level in accordance with the divided resistance on the film resistors 10a and 10b. The voltage signal is provided from the X direction transparent film resistor 10a and the Y direction transparent film resistor 10b to be applied to the CPU 1 as XY coordinate values via the A/D converter 8. The CPU 1 drives the display controller 12 in response to the applied coordinate values, whereby the controller 12 drives the corresponding elements on the display device 11 for display. Thus, when a user depresses a desired position on the tablet 10, the depressed position can be confirmed visually by screen display.
In the above-described display integrated type tablet apparatus where the display device 11 and the tablet 10 of transparent film resistors 10a and 10b are integrated, there was a problem of lowering the accuracy of the coordinate measurement because of noise mixed into the voltage signal entering the A/D converter 8 caused by the driving signal from the controller 12 to the display device 11. That is to say, there was a problem of generation of reading out coordinates without order. Therefore, means were provided for reducing noise in the detected signal of the display integrated type tablet apparatus as shown in FIGS. 9 and 10. Referring to FIG. 9, condensers CX and CY for noise removal were inserted in the X direction and the Y direction, respectively, at the terminals for coordinate measurement, i.e. input terminals of the A/D converter 8. Referring to FIG. 10, noise is reduced in the detected signal from the tablet 10 due to driving the display device 11 by increasing the distance L.alpha.between the display device 11 and the tablet 10 (the Y direction transparent film resistor 10b).
By such means, noise overlaid in the detected coordinates, i.e. the detected voltage signal, of the tablet 10 is reduced to suppress measurement error significantly.
However the above-described means for noise reduction had the following problems.
In the case where particular elements for noise reduction such as condensers CX and CY are provided as shown in FIG. 9, it was technically difficult to completely remove noise only with these noise reduction elements. There was a problem of increase in the cost of the apparatus itself due to the number of components being increased even by the additional provision of these elements.
By increasing the distance L.alpha. between the display device 11 and the tablet 10 as shown in FIG. 10, the distance between the main surface of the tablet 10 and the screen of the display device 11 was unnecessarily increased to result in inadequate parallax. There was also a problem that the thickness of the apparatus is increased in the case of a structure where the tablet 10 and the display device 11 are formed integrally.
The display integrated type tablet apparatus as a man-machine interface is becoming increasingly important with the need of a larger screen, higher accuracy (corresponding to the critical display drive of the display device), lower power consumption, and lower cost. Although the above described method employing transparent film resistors 10a and 10b is superior from the standpoint of low cost and low power consumption, the amount of noise is increased from the display device 11 in accordance with increase in the screen size, resulting in lowering the position reading accuracy. That is to say, because the tablet 10 and the display device 11 establish an electrostatic capacitive coupling, there is a disadvantage of increase in the amount of noise included in the position read out signal in proportion to the area size of the main surface of the tablet 10.

Display integrated type position reading apparatus


A process for removing unwanted contaminant metallic oxide from the surface of a nickel branding layer of an electronic circuit package, in order to enhance the affinity of a layer of phenolic branding ink to the surface of the metallic branding layer involves treating the surface of the metallic branding layer with a hydrogen-containing, chemical reducing gas phase ambient, so that oxygen within the surface oxide chemically combines with the hydrogen component within the ambient, so as to form readily removable water. The surface of the metallic branding layer is thereby substantially free of surface oxide, providing a greater surface area of metallic-ink bonding sites. As a consequently, a subsequently deposited layer of branding ink strongly adheres to the surface of the nickel and is not readily removed during further cleaning of the circuit package.

The manufacture of electronic circuit components and the packaging of those components customarily involves the deposition of one or more layers of material upon a base element or substrate. During the manufacturing process it is occasionally necessary to subject the component to a cleansing purge to remove unwanted contaminants that may have formed in a previous process step and to prepare the part for the formation of additional material on one or more selected sites. For example, to maximize the metallurgical affinity of solder (diagrammatically shown at 11 in FIG. 1) to an electrode terminal 13, the terminal metal should be free of surface contaminant material (e.g. oxide and organics) 15, before application of the solder. Similarly, with reference to the diagrammatic illustration of an electronic circuit package 20 in FIG. 2, prior to depositing a layer of `branding code` ink 21 to the surface 23 of a metallic (e.g. nickel) branding lid 25, it is necessary to clean the surface of the metallic branding lid 25, in order ensure that the ink will strongly adhere to the lid and tolerate various solvents that are used to clean the part before and after it is eventually soldered in place on an electrical circuit board.
Conventional branding techniques on nickel-plated circuit packaging lids involve the use of a number of ink supplier-recommended wet chemical etching solutions, such as Markum 535, Markum 310, IPA, which have been accepted by the industry as being effective in removing oxide and organic contaminants, thereby sufficiently increasing the surface energy of the lid to the adherence of the ink to meet MIL-STD testing compliance for brand permanency. In effect, the chemical solution physically etches away the surface of the lid and thereby removes surface oxide and organics down to some level of `clean` metal, in order that the number of uncontaminated nickel bonding sites will be increased.
Unfortunately, chemical etching solutions have a significant drawback, - the entire circuit package is immersed in the etching solution in order to clean or etch the oxide contaminants off the lid. As a consequence, the solution not only cleans the lid, but, because of its substantial caustic properties (Markum 535, for example, contains monoethanolamine which has a pH greater than ten), it etches or physically attacks other portions of the package, such as the soldered leads, the lid-to-seal ring weld area, and various plated metallic markings or codes on the package, as well as the ceramic package itself. It has been found that this ancillary etch not only degrades the cosmetic appearance of the part, but may detrimentally affect its overall reliability. Moreover, upon completion of the chemical etch, because the package is subjected to an oven drying step at an elevated temperature, following a rinse, oxide again begins to immediately form on the `cleaned` surface of the nickel. As a result, when the part emerges from the drying oven, time is of the essence for successfully depositing the branding ink, which must ordinarily conducted within minutes of the oven drying step.

Gas phase chemical reduction of metallic branding layer of electronic circuit package for deposition of branding ink


A Pr1-XCaXMnO3 (PCMO) spin-coat deposition method for eliminating voids is provided, along with a void-free PCMO film structure. The method comprises: forming a substrate, including a noble metal, with a surface; forming a feature, such as a via or trench, normal with respect to the substrate surface; spin-coating the substrate with acetic acid; spin-coating the substrate with a first, low concentration of PCMO solution; spin-coating the substrate with a second concentration of PCMO solution, having a greater concentration of PCMO than the first concentration; baking and RTA annealing (repeated one to five times); post-annealing; and, forming a PCMO film with a void-free interface between the PCMO film and the underlying substrate surface. The first concentration of PCMO solution has a PCMO concentration in the range of 0.01 to 0.1 moles (M). The second concentration of PCMO solution has a PCMO concentration in the range of 0.2 to 0.5 M.

1. Field of the Invention
This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to a PCMO deposition process that forms a void-free interface with an underlying noble metal substrate.
2. Description of the Related Art
Pr1-XCaXMnO3 (PCMO) thin films have been found to have unique resistance change properties. With the application of a narrow nanosecond pulse, having an amplitude of 5 volts and a duration of 100 nanoseconds, the resistance can be changed to a high resistant state. Likewise, if a wider microsecond pulse is applied, the resistance can be reset to its initial (low-resistance) state. The observed change in resistance states is in the range of one to three orders of magnitude. Further, a resistance state changes can be affected in a PCMO film with the application of an opposite amplitude polarity narrow (nanosecond range) pulses. Thus, the resistance state of the PCMO film can be controlled using uni-polarity (a narrow and wide pulse having the same amplitude polarity) and bipolar (opposite amplitude polarity narrow pulses) programming. These programming characteristics make the PCMO well suited for use in memory cells and resistor RAM (RRAM) applications. These memory cell devices typically employ at least one electrode made, at least partially, from a noble metal, adjacently located to the PCMO memory resistor material.
There are many methods used for PCMO thin film deposition, such as physical vapor deposition (PVD), metalorganic chemical vapor deposition (MOCVD), and spin-coating. Of the three, spin-coating is one of the best candidates for the large scale manufacturing, as it is a relatively low cost, easy process.
FIG. 1 is a drawing depicting a PCMO film, formed using a conventional spin-coating process, overlying a Pt electrode (prior art). As can be seen in the figure, a void is formed in the interface between the PCMO and Pt layers. The problem is likely a result of the poor wetting properties of the PCMO spin-coating solution on the Pt surface. These voids are extremely detrimental to performance of RRAM devices. The voids encourage the formation of shorts between the top and bottom electrodes and degrade (increase) the leakage current. Further, the voids may result in the PCMO film being peeled from the Pt substrate during subsequent fabrication processes, such as during a chemical mechanical polish (CMP) step.
It would be advantageous if PCMO film could be consistently formed, without voids, on a noble metal substrate.
It would be advantageous if the above-mentioned void-free PCMO film could be formed using a spin-coating process.


A method of validating a public key comprising the steps of receiving a public key, computing a function of the public key, the function having a predefined value for all points of a given order, and comparing the result of the function to predetermined information to indicate the validity of the public key.

1. Field of the Invention
This application relates to a method and apparatus for performing validation of elliptic curve public keys.
2. Description of the Prior Art
Cryptography is an essential tool in information security. It allows two correspondents to communicate secretly and/or authentically over a public channel. Private key systems require a secret to be shared beforehand by the correspondents. Such key distribution is often as difficult as the initial problem of secret communication, since the secret key must be transferred over a secure channel.
Public key cryptography helps solve the otherwise intractable problem of key distribution in cryptography. Without public key cryptography, the difficulty of key distribution is so high that securing information is impractical for all but those with the most extensive resources. Elliptic curve cryptography is a very efficient variety of public key cryptography, which is highly suitable for a wide variety of constrained environments. Other well-known varieties of public key cryptography include RSA and (ordinary) Diffie-Hellman.
Public key validation involves making sure that the public keys have the requisite properties, which ensures that no security compromises result from processing invalid public keys. For elliptic curve cryptography, some of the security compromises that can result from processing invalid public keys include small subgroup attacks and invalid-curve attacks.
Elliptic curve public key validation comes in two varieties, as set forth in the standards ANSI X9.62 and ANSI X9.63, namely partial validation and full validation. Elliptic curve public keys are elliptic curve points, and for a given set of elliptic curve domain parameters, a given point can be either valid or not valid. Elliptic curve domain parameters consist of a finite field size q together with a given representation FR of field elements, coefficients a and b of the elliptic curve equation, a prime number n, a cofactor h, and a base point or generator G. Suppose that Q is purported to be a valid elliptic curve point for domain parameters (q, FR, a, b, n, h, G). The point Q is fully valid if the following four conditions are met:
1. Q is not 0, the point at infinity (also known as the identity, zero or neutral element of the elliptic curve);
2. Q=(x, y) where x and y are valid elements of the finite field of size q for the given field representation FR;
3. E (x, y)=0, where E is given by the equation for the elliptic curve. For prime q>3, this means that y2=x3+ax+b, and for even q, this means that y2+xy=x3+ax2+b;
4. nQ=0, where, nQ means Q added n times to 0, called a scalar multiple of Q.
If the first three conditions hold, then Q is said to be partially valid.
The straightforward way to check condition 4 is to do scalar multiplication. However, scalar multiplication is a computationally intensive step of elliptic curve cryptography. The computation cost of typical operations in elliptic curve cryptography, such as signing, verifying, encrypting and decrypting, is roughly equal to somewhere between one to one-and-a-half scalar multiplications. Therefore, full validation, at least using the straightforward methods, roughly doubles the computational cost. In practice, therefore alternate techniques are used to thwart some of the attacks, such as small subgroup attacks, that full validation seeks to prevent.
Some elliptic curve cryptographic schemes use the so-called cofactor method. Here the public key Q is scalar multiplied by h before further use. Then n(hQ)=0, which prevents many types of small subgroup attacks. In such cases, partial validation of Q suffices to prevent these attacks. For the small h values typically used, such as 1,2 and 4, the cofactor method is much more efficient than the straightforward method of doing full validation, because computing hQ for small h is much faster than computing nQ since n is a large prime.
Another method is the so-called compatible cofactor method, which is first scalar multiplying Q by h, as above, getting a result hQ so that n(hQ)=0, and then scalar multiplying by h−1 mod n. If Q has order n to begin with, the result of these two steps is Q itself, and thus the term compatible. If Q does not have order n, the result of the operations has order n but is different from Q. Generally, the compatible cofactor method requires computing a full scalar multiplication so is no more efficient than the obvious method of doing full validation.
It should be noted that when the cofactor h=1, partial validation and full validation are equivalent. That is, when h=1 no extra steps are necessary beyond those in partial validation to accomplish full validation.
The known small subgroups attacks that full validation thwarts compromise log2(h) bits of elliptic curve private keys. There may, however, be more damaging attacks exploiting not fully validated elliptic curve points, which are as yet undiscovered. As a precaution, therefore, full validation is highly recommended, wherever possible. A common practice, however, has been to use partial validation. When partial validation is not supplemented by one of the alternate techniques above, such as the cofactor method, the known attacks reduce the security by log2(h)/2 bits, and the unknown attacks might reduce it by more.
It is an object of the present invention to obviate or mitigate some of the above disadvantages.

Method and apparatus for performing validation of elliptic curve public keys


The present application relates to a method for preparing a foot-and-mouth disease (FMD) vaccine, comprising the following steps: (i) obtaining cell culture media containing FMD virus; (ii) separating and purifying the cell culture media containing FMD virus by an integrated filtration system with two membranes in combination; and (iii) collecting the concentrated solution containing FMD virus obtained in step (ii). The present application also relates to an FMD vaccine prepared by the method described herein and use thereof in the manufacture of a medicament for preventing animal FMD. The present application further relates to an apparatus for preparing an FMD vaccine, which comprises an integrated filtration system with two membranes in combination.

FMD is an acute, febrile, highly contagious infectious disease in animals caused by FMD viruses. FMD mainly invades cloven-hoofed animals, and its features for clinical diagnosis include blisters on the skin of oral mucosa, hooves and breast. A variety of FMD vaccines have been developed to control and prevent FMD at present. Regarding the method for preparing FMD vaccines, a simple combination of various separation and purification procedures is currently used in the art. For example, continuous flow centrifugation combined with straight flow filtration, depth filtration, or hollow fiber filtration, PEG precipitation or chromatography, and other means are used to separate and purify the harvested cell culture media containing FMD virus, so as to obtain purified FMD virus vaccines.
However, it is difficult for such a simple combination of the separation and purification procedures to achieve the optimum separation and purification efficiency of each procedure, resulting in an extreme imbalance of product quality, production efficiency, and production cost, which is undesirable.

Method for preparing foot-and-mouth disease vaccines


An information processing apparatus and a method for managing dispensing information associated with a prescription for medicine, the apparatus and method including inputting acquiring information for acquiring dispensing status information associated with a prescription for medicine, sending the input acquiring information to at least one other device, and receiving the dispensing status information acquired based on the acquiring information from the at least one other device.

1. Field of the Invention
The present invention relates to an information processing apparatus, an information processing method, and a program for sending/receiving data to/from an external device.
2. Description of the Related Art
A prescription describes a medicine prescribed for a patient as a result of a diagnosis in a medical institution, such as a hospital and a clinic.
Generally speaking, a patient gets a prescription issued by a medical institution, and takes the prescription to an external pharmacy that is open outside the medical institution. Then, the pharmacy dispenses a medicine in accordance with the prescription, and the patient receives the dispensed medicine. In this case, the pharmacy does not know the medication contents to be dispensed until it gets the prescription. Only after the patient takes the prescription to the pharmacy can the pharmacy begin dispensing a medicine.
To shorten the time for a patient to wait in a pharmacy, a prescription may be sent to the pharmacy in advance by fax, and a medicine may be dispensed before the patient goes to the pharmacy. According to this method, the patient does not know how busy the pharmacy is at the time of sending the prescription thereto. Therefore, even if the medical institution or doctor sends the prescription beforehand, the patient might still have to wait in the pharmacy. Another problem is that it is difficult to select an optimum external pharmacy from a plurality of external pharmacies.
Japanese Patent Application Laid-Open No. 2003-263501 discusses a method for shortening the time for a patient to wait in a pharmacy when a prescription is sent beforehand. According to this method, a display unit of a prescription sending apparatus displays a map of each external pharmacy and the time to wait for the dispensation in the pharmacy. Then, a patient specifies one pharmacy and the time to pick up a medicine when the patient sends a prescription to the specified pharmacy using the prescription sending apparatus.
However, the dispensation of the prescription is not necessarily done in sequential order. The medication may not be dispensed sequential order due to the contents of the received prescription. For example, the medicine for a patient of a serious case is dispensed on a priority basis. Thus, dispensing of the medication may not necessarily be completed on time as estimated.
According to Japanese Patent Application Laid-Open No. 2003-263501, after the prescription is sent to the pharmacy, the patient does not know the general dispensing (preparation) status of the sent prescription in the pharmacy, and does not know the dispensing status of the sent prescription in real time. Additionally, it is very difficult for a patient to change the selected pharmacy once the prescription has been sent to the pharmacy. In addition, in many instances due to the patient's schedule, it is also difficult to change when the patient is able to go to the pharmacy to pick up the prescription.

Information processing apparatus, information processing method, and computer program


An LED light dedusting/cooling system includes a housing receiving therein a control member, a fan, a heat sink and an LED module. The fan and the LED module are respectively disposed on two opposite sides of the heat sink. The LED light dedusting/cooling system further includes a vibrator received in the housing and disposed on one side of the heat sink proximal to the fan and positioned between the heat sink and the fan. In operation, the vibrator can vibrate between the heat sink and the fan to shake (or shock) off the dust or alien articles attaching to the fan and the heat sink. Then, the fan operates to blow out the dust from the housing.

1. Field of the Invention
The present invention relates generally to a lighting device, and more particularly to an LED light dedusting/cooling system.
2. Description of the Related Art
It is known that LED is a sort of solid semiconductor element capable of directly converting electrical energy into visible light. In comparison with the conventional light, the LED light has the advantages of high brightness, low energy consumption, long lifetime, energy saving and environmental protection. Therefore, the conventional halogen lights and fluorescent light tubes have been rapidly replaced with the LED lights.
In order to increase the luminous flux of the LED light, that is, increase the brightness of the LED light, various high-power LED lights have been developed and sold by many manufacturers. Due to the limitation of volume and the requirement of installation of sealing-type or semi-sealing-type housing, the LED light is generally inbuilt with an active heat dissipation device including a fan and radiating fins, especially with respect to such as projection lamp, down lamp, bulb lamp and cap lamp that employ LED lights. Such lighting device has some shortcomings that the use frequency is high and the use time is long. As a result, during a long-term operation, the inbuilt fan will take in a great amount of alien articles such as dust and hairs to accumulate in the interior space of the housing and on the surface of the heat dissipation device. This often leads to deterioration of the efficiency of the active heat dissipation device or even malfunction of the fan. In this case, the LED light will burn out due to overheating.


A kit for capturing a first primary image and a second backup image from a single exposure. The kit may include a first imaging source and a second imaging source. The kit may further include an attachment mechanism for attaching the first imaging source to the second imaging source such that first imaging source and the second imaging source may be simultaneously exposed to capture a first primary image and a second backup image, respectively, of a same anatomy. The kit may further include a sterilization sheath to cover both the first imaging source and the second imaging source when the first imaging source and the second imaging source are attached and being used to capture images.

Various types of imaging systems are available for imaging the surface and/or the interior of such diverse entities such as, for example, the human anatomy, animals, man-made physical structures such as welding joints in bridges, geological formations, bodies of water, as well as many others. For example, in the field of dentistry, various types of intra-oral sensors exist which are used for capturing images of the inside of teeth and surrounding anatomy (e.g., bone structure) by exposing the anatomy and sensors to X-ray radiation. Such imaging techniques are well known using such intra-oral sensors as, for example, X-ray sensitive film, X-ray sensitive phosphor plates, or X-ray sensitive digital sensors such as a corded charge-coupled device (CCD) sensor, for example.
When capturing an image, sometimes the sensor may fail. For example, if the sensor is a film, the film may have gone bad due to age, been damaged somehow, or may have been prematurely exposed for some reason. If the sensor is a phosphor plate, the plate may have been damaged or the plate may not have been properly erased after a previous exposure. If the sensor is a corded digital CCD sensor, the system to which the sensor is connected may fault, thus failing to extract the image information from the CCD sensor. Other mechanisms of failure are possible as well with respect to properly capturing and storing an image.
Such failures or faults may result in the operator (e.g., an imaging technician or physician) having to go back and re-expose the patient in order to attempt to capture a proper image of the desired anatomy. Furthermore, if the operator does not immediately realize that a failure has occurred, an image of a particular desired anatomy may not be acquired at all during a scanning session, resulting in inadequate information being provided to the physician.
Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such systems and methods with the present invention as set forth in the remainder of the present application with reference to the drawings.