A mechanical component has a recess for receiving a ceramic insert. The insert is held in the recess by a retainer member which preferably resiliently biases the insert inwardly into the recess. The insert provides a hardened bearing surface for the associated mechanical component. For example, the mechanical component may be a piston for use in an engine brake (especially as a master piston in the engine brake), and the ceramic insert may be the portion of the piston assembly which contacts a moving part of the internal combustion engine with which the engine brake is used.

This invention relates to mechanical assemblies of initially separate parts, and more particularly to mechanical assemblies which include hardened bearing surface elements secured to other members. For example, the invention may be applied to attaching a hardened bearing element to a piston (especially a master piston) in a compression release engine brake or to a cam follower in an internal combustion engine.
Although those skilled in the art will appreciate that the invention has many other applications, the invention will be fully understood from the following discussion which is chiefly in the context of applying hardened bearing surfaces to the master pistons in compression release engine brakes.
Meistrick et al. U.S. Pat. No. 4,706,625 (which is hereby incorporated by reference herein) shows a typical prior art engine brake. As shown in FIG. 1 of that patent, the typical engine brake includes hydraulic circuits, each of which (when the engine brake is on) transfers the motion of one part of the associated internal combustion engine (e.g., fuel injector rocker arm 72) to another part of the engine (e.g., sliding pin 51) to open an exhaust valve 60 in a cylinder which is at or near the end of its compression stroke. This releases the gas compressed by the piston in that cylinder and prevents the energy of compression from being recovered during the subsequent expansion stroke of the cylinder. Dissipation of energy in this way helps to slow down, retard, or brake the engine and the associated vehicle.
As shown in FIG. 1 of the '625 patent, each hydraulic circuit in an engine brake typically includes a master piston 66 and a slave piston 50. In the particular engine brake shown in '625 patent FIG. 1, adjusting screw 70 on rocker arm 72 bears on the lower surface of master piston 60 when the engine brake is on so that master piston 60 is driven to reciprocate by the arcuate reciprocation of the adjusting screw. The area of contact between adjusting screw 70 and master piston 66 is one of the highest stress regions in the engine brake. The top of the adjusting screw may be convex to avoid an edge of the screw contacting the master piston when the adjusting screw rocks due to oscillation of rocker arm 72. This convexity reduces the area of contact between the adjusting screw and the master piston, thereby contributing to the high stress in the contact area. The arcuate motion of adjusting screw 70 also causes the top of the screw to slide back and forth on the master piston surface it contacts, thereby increasing the tendency of the contacting surfaces to wear. To reduce this wear it has been necessary to ensure good lubrication between the master piston and the engine component such as adjusting screw 70 which contacts it. It has also been known to weld a layer of tungsten carbide material to the wear surface of the master piston. For example, such a tungsten carbide layer may be 0.014 to 0.015 inches thick.
Engine performance is constantly being pushed to higher levels. Increased engine performance leads to even higher stress on the master piston in an associated engine brake. This may cause the above-mentioned tungsten carbide layer to crack. Unfortunately, tungsten carbide can only be deposited on the master piston in a relatively thin layer as mentioned above. Engine manufacturers are also now interested in so-called "dry engines." These are engines employing much less lubricant than has been traditionally employed. Reduced lubricant reduces the horsepower required for lubricant pumping, and also reduces the amount of combusted lubricant (and therefore pollutants) in the engine exhaust. From the standpoint of engine brake manufacture, however, a dry engine is an even more severe operating condition because there is less lubricant available for lubricating the engine brake master piston surfaces which receive the driving inputs from the associated engine.
Substitution of a ceramic such as silicon nitride (Si.sub.3 N.sub.4) for the tungsten carbide on master pistons has been considered. This would be advantageous because silicon nitride has a modulus of elasticity close to that of the bearing steel (e.g., so-called 52100 bearing steel) typically used for parts such as the adjusting screw 70 which contact the master piston in FIG. 1 of the '625 patent. However, silicon nitride has a coefficient of thermal expansion which is much less than (e.g., only about one-sixth) the coefficient of thermal expansion of the steel used to make master pistons. This makes secure attachment of a ceramic element to a master piston difficult, especially in view of the fact that the ceramic element would typically be on the lower surface of the associated master piston, where it would be out of contact with any part of the engine when the engine brake is off.
In view of the foregoing, it is an object of this invention to facilitate the provision of mechanical components with securely attached ceramic bearing surface elements.
It is a more particular object of this invention to provide engine brake pistons (especially master pistons) with securely attached ceramic inserts for use as bearing surfaces.

Mechanical assemblies with hardened bearing surfaces


A control circuit and method are provided to generate a modulation signal to operate a power stage in a DC/DC PWM converter such that the DC/DC PWM converter is controlled to operate with high switching frequency in light load stead state, once load transient happens, it still operates with high switching frequency for good transient response, and in heavy load stead state, it is controlled to operate with low switching frequency for good efficiency.

As shown in FIG. 1, a four-channel DC/DC PWM converter 10 comprises a control circuit 12 to manipulate a four-channel power stage 14, and each channel of the power stage 14 comprises two transistors 1404 and 1406 connected in series between an input voltage Vin and ground GND, in which the transistors 1404 and 1406 are alternatively switched by one of four modulation signals PWM[1] to PWM[4] provided by the control circuit 12, so as to produce four channel currents IO1 to IO4 respectively. The channel currents IO1 to IO4 are combined to an output current IO to charge a capacitor C to thereby produce an output voltage VO. The control circuit 12 monitors the channel currents IO1 to IO4 and the output voltage VO, in order to modulate the duty cycle of the transistors 1404 and 1406 in the power stage 14. FIG. 2 shows a circuit diagram of a conventional control circuit 12, in which a channel-current sensor 1236 senses the channel currents IO1 to IO4 to produce four current-sensing signals Ix[1] to Ix[4] respectively, a combiner 1234 combines the current-sensing signals Ix[1] to Ix[4] to produce a summing signal ISUM which flows through a resistor RADJ connected between a pin ADJ and ground GND to produce an adjusting voltage VADJ, a digital-to-analog converter (DAC) 1202 converts a digital voltage signal VID[n:0] to an analog voltage VIA, a combiner 1204 combines the analog voltage VIA with the adjusting voltage VADJ to produce a reference voltage signal Vref1, an error amplifier 1206 monitors the output voltage VO by comparing a feedback signal FB proportional to the output voltage VO with the reference voltage signal Vref1 to produce an error signal VEA, four ramp generators 1210, 1212, 1214 and 1216 generate four ramp signals RAMP[1], RAMP[2], RAMP[3] and RAMP[4] respectively under a clock CLK provided by an oscillator 1208 according to the voltage on a pin OSC, a combiner 1218 shifts the level of the ramp signal RAMP[1] by the current-sensing signal Ix[1] to produce a ramp signal RAMP[1]′, a comparator 1226 compares the error signal VEA with the ramp signal RAMP[1]′ to produce the modulation signal PWM[1] for the first channel of the power stage 14, a combiner 1220 shifts the level of the ramp signal RAMP[2] by the current-sensing signal Ix[2] to produce a ramp signal RAMP[2]′, a comparator 1228 compares the error signal VEA with the ramp signal RAMP[2]′ to produce the modulation signal PWM[2] for the second channel of the power stage 14, a combiner 1222 shifts the level of the ramp signal RAMP[3] by the current-sensing signal Ix[3] to produce a ramp signal RAMP[3]′, a comparator 1230 compares the error signal VEA with the ramp signal RAMP[3]′ to produce the modulation signal PWM[3] for the third channel of the power stage 14, a combiner 1224 shifts the level of the ramp signal RAMP[4] by the current-sensing signal Ix[4] to produce a ramp signal RAMP[4]′, a comparator 1232 compares the error signal VEA with the ramp signal RAMP[4]′ to produce the modulation signal PWM[4] for the fourth channel of the power stage 14, and a resistor ROSC is connected between the pin OSC and ground GND for setting the switching frequency of the power stage 14.
FIG. 3 shows a conventional circuit for one channel of the channel-current sensor 1236, in which a transconductive amplifier 12362 senses the channel current IO1 flowing through a sensing resistor R1, so as to produce a voltage dropVS=IO1×R1  [Eq-1]and due to the virtual short between the inputs CSP and CSN of the transconductive amplifier 12362, the voltage drop across a resistor Rx1 is equal to the voltage VS, and therefore the transconductive amplifier 12362 produces the current-sensing signalIx[1]=VS/Rx1=(IO1×R1)/Rx1   [Eq-2]
For a DC/DC PWM converter, it is very important to control the switching frequency of the transistors 1404 and 1406 in the power stage 14. FIG. 4 shows a waveform diagram of the output current IO and the output voltage VO when the transistors 1404 and 1406 are switched with low switching frequency, in which waveform 20 represents the output current IO, waveform 22 represents the adjusting voltage VADJ, waveform 24 represents the output voltage VO, and waveform 26 represents the average voltage VO(AVG) of the output voltage VO. As the load changes from light to heavy, the output current IO suddenly increases as shown by the waveform 20, the adjusting voltage VADJ also increases with the increasing output current IO as shown by the waveform 22 since it is proportional to the output current IO, the output voltage VO drops down to a lower level until the load changes from heavy back to light, and then the output voltage VO will recover to the previous level, as shown by the waveform 24. In this case, because the switching frequency is low, the power stage 14 is not easy to heat when the load is heavy, thereby having good efficiency. However, due to the low switching frequency, as shown by the waveform 26, the output voltage VO cannot keep at a predetermined level immediately when the load transient happens, and hence lower when changing from light load to heavy load and higher when changing from heavy load to light load, causing poor transient response.
FIG. 5 shows a waveform diagram of the output current IO and the output voltage VO when the transistors 1404 and 1406 are switched with high switching frequency, in which waveform 30 represents the output current IO, waveform 32 represents the adjusting voltage VADJ, waveform 34 represents the output voltage VO, and waveform 36 represents the average voltage VO(AVG) of the output voltage VO. As the load changes from light to heavy, the output current IO suddenly increases as shown by the waveform 30, the adjusting voltage VADJ also increases with the increasing output current IO as shown by the waveform 32 since it is proportional to the output current IO, the output voltage VO drops down to a lower level until the load changes from heavy back to light, and then the output voltage VO will recover to the previous level, as shown by the waveform 34. In this case, as shown by the waveform 36, because the switching frequency is high, the output voltage VO can keep at a predetermined level immediately when the load transient happens. However, the power stage 14 is easy to heat when the load is heavy, due to the high switching frequency, thereby resulting in poor efficiency, as shown by the waveform 34.
Therefore, it is desired a control circuit and method to improve both heavy load efficiency and load transient response of a DC/DC PWM converter.

Frequency-on-the-fly control circuit and method for a DC/DC PWM converter


The technology relates to a telescoping support structure which can be suspended between two objects. The telescoping support structure uses projections between adjacent tubular sections in order to prevent the adjacent tubular sections from falling away from one another. Although the telescoping support structure may be utilized in various different environments and circumstances, it may be of particular usefulness in the field of high-altitude ballooning. For instance, when used in a balloon system, the telescoping support structure may be suspended between two objects such as an upper payload structure and a lower payload structure. As another example, the telescoping support structure may be suspended between a balloon envelope and a payload which, in some examples, may include an upper and a lower payload structure.

Computing devices such as personal computers, laptop computers, tablet computers, cellular phones, and countless types of Internet-capable devices are increasingly prevalent in numerous aspects of modem life. As such, the demand for data connectivity via the Internet, cellular data networks, and other such networks, is growing. However, there are many areas of the world where data connectivity is still unavailable, or if available, is unreliable and/or costly. Accordingly, additional network infrastructure is desirable.
Some systems may provide network access via a balloon network. However, the size of the balloons, payloads and connections there between required to provide such access, can become quite large, reaching 50 meters or more or less. This can create logistical issues as well as difficulties prior to and during launch of these balloons.


In an example, a method includes forming a layer of build material, processing a first portion of the build material by distributing a print agent using a first distribution pattern, the first distribution pattern having a first print agent dispersion characteristic and processing a second portion of the build material by distributing a print agent using a second distribution pattern, the second distribution pattern having a second print agent dispersion characteristic. The method may further include heating the build material by exposing the layer of build material to radiation so as to cause fusing of the first and second portion.

Three-dimensional (3D) printing is an additive manufacturing process in which three-dimensional objects may be formed, for example, by the selective solidification of successive layers of a build material. The object to be formed may be described in a data model. Selective solidification may be achieved, for example, by fusing, binding, or solidification through processes including sintering, extrusion, and irradiation. The quality, appearance, strength, and functionality of objects produced by such systems can vary depending on the type of additive manufacturing technology used.

Determining distribution patterns for object portions

Hewlett-Packard Development Company, L.P.


A footrest for a conventional toilet that may be conveniently stored in a nested position under the toilet bowl. The footrest has a left side frame and a right side frame that are connected at their forward ends by a telescoping connecting member. The side frame members each a vertically oriented U-shaped portion that is connected to a cantilever portion having foot platforms mounted thereon. The footrest is used to facilitate a toilet user assuming a semi-squatting position during use. The footrest may also be used by children or other person's whose legs do not reach the floor when on the toilet.

The invention relates to a footrest and more particularly to devices that control the position of a person sitting on a toilet.
It is well known the toilet construction currently in use in the western world, including both the toilet bowls and the toilet seats, are not designed to take full advantage of the toilet user's physiological functions. Current toilet construction usually comprises a bowl attached to an inwardly sloping support and a seat of generally horizontal orientation. In brief, the shape of conventional toilets significantly interferes with blood circulation in the user's legs. Furthermore, the user's sitting position while on the toilet tends to compress the user's buttocks, thereby hampering the elimination process. It is significant that poor blood circulation and strain are among the leading causes of the painful condition of hemorrhoids.
Various studies regarding the toilet and elimination process have suggested that to maximize elimination efficacy and minimize strain on the toilet user, the user should assume a semi-squat position on the toilet. In this position, the user's thigh muscles, resting against the upper groin area, can result in the elimination of a larger percentage of excrement from the body.
In addition, the conventional toilet is made of a size to suit the average adult person. Thus, the conventional toilet is difficult to use by small children or other persons with very short legs. The short legs tend not to reach the ground and dangle unsupported. The person may experience discomfort or insecurity due his dangling legs while using the toilet.
The prior art comprises sculpted toilet seats and foot rests for the toilet user. The sculpted toilet seats, which replace conventional seats, have elevated and depressed portions arranged so that (1) the user's buttocks are left uncompressed or (2) the user is urged to lean forward during the elimination process. In either case, the user relieves some of the strain otherwise encountered during the elimination process. Alternatively, the footrests are either permanently attached to the toilet bowl support or temporarily hooked over the upper lip of the toilet bowl, usually between the existing seat and the bowl.
The prior art devices have three major drawbacks. First, devices that are permanently attached to the toilet do not allow a toilet to be used in the conventional manner. Second, the detachable devices need a place for storage and often require more time to set up than is available when a person needs to use the toilet. Third, the devices in general are decoratively unattractive or intimidating to the user.
It is an object of the invention to provide a novel footrest that is easily and quickly stored under the bowl of the toilet.
It is also an object of the invention to provide a novel footrest for a toilet that is not attached to the toilet bowl or tank.
It is another object of the invention to provide a novel footrest for a toilet that is economical to manufacture and market.
It is a further object of the invention to provide a novel footrest for a toilet that can be used by children and adults.


A method of forming an active area surrounded with an insulating area in a semiconductor substrate, including the steps of forming in the substrate a trench surrounding an active area; filling the trench with an insulating material to form an edge extending beyond the substrate surface at the periphery of the active area; forming a spacer at the periphery of said edge; and implanting a dopant, whereby the implantation in the area located under the spacer is less deep than in the rest of the active area.

The present invention generally relates to integrated circuits on a semiconductor substrate including at least one component formed in an active area and more specifically to the forming of active areas surrounded with insulating areas. These insulating areas are obtained from trenches filled with an insulating material and each active area is intended for receiving a conductive layer insulated therefrom, for example a control gate of a device of transistor type. The device may be a MOS transistor formed by any known technology (MOS, CMOS, BiCMOS).
FIG. 1 partially and schematically illustrates in a transversal cross-section view a semiconductor substrate 1 on which is formed an insulated conductive line. It is considered hereafter as a non-limiting example that this line is a gate electrode of a MOS transistor of lateral type.
In FIG. 1, substrate 1 includes an active area 5 delimited by an insulating area 2. Insulating area 2 has been formed by digging trenches into the substrate, then by filling them with an insulating material, typically silicon oxide (SiO2). The filling is performed so that the insulating material overflows, as indicated by dotted line 6, with respect to the level defined by the substrate, whereby insulating area 2 has a top having a substantially planar surface at a level higher than the surface of the active area 5 thus defined, this top ending in a substantially vertical edge leading to active area 5. Such an insulating area structure 2 can be conventionally obtained in several ways, as will be discussed hereafter.
Insulating area 2 has, in contact with active area 5, an embattling area which, due to overetchings in subsequent steps of removal of various sacrificial insulating materials, will cause a depression 7 at the periphery of active area 5.
At the level of a gate area, a thin insulator layer 3 covers the upper surface of active area 5 as well as its peripheral portion exposed by depression 7. Layer 3 is covered with a layer 4 of a conductive material, typically polysilicon. Conductive material 4 passes over insulating area 2 and over active area 5, and fills depression 7. The filling of depression 7 by the gate material has disturbing effects. Indeed, because of the curvature exhibited on the edge of active area 5 by the gate material due to this depression, the distribution of the electric field in the channel area located at the edge of insulating area 2 is disturbed, which deteriorates, as will be seen hereafter, the transistor performances.
FIG. 2 illustrates in top view a MOS transistor of lateral type. In this case, FIG. 1 corresponds to a partial cross-section view along line Axe2x80x94Axe2x80x2, limited by an area defined by the dotted lines. Active area 5 includes a channel area, located under a control gate 4 and, on either side of the gate, source and drain regions. The gate, drain, and source contacting points are underscored by hatched regions, the location of which is indifferent to the discussion of the present invention.
Depression 7 exhibited by insulating layer 2 is located over the entire periphery P of active area 5. The portions of periphery P underlying the gate are underscored by check patterns 8 and it can be considered that the MOS transistor of FIG. 2 is formed of two transistors: a central transistor with normal performances, having a planar gate parallel to the surface of substrate 1 and, on either side of the central transistor, a parasitic transistor with impaired performances located along insulating layer 2, having a non-planar gate extending over depression 7.
FIG. 3 shows the drain-source current Ids, in logarithmic coordinates as a function of gate-source voltage Vgs. Curve C1 corresponds to the central transistor and has a normal threshold voltage V1 and a normal leakage current I1off (current Ids for Vgs=0). Curve C2 corresponds to the parasitic transistor and has a decreased threshold voltage V2 and an increased leakage current I2off. Since the resulting MOS transistor has a characteristic corresponding to the sum of curves C1 and C2, its threshold voltage will also be lowered and, above all, its leakage current Ioff will be increased. This causes leakages, which are very disturbing, for example, in applications where the considered transistor belongs to a chip powered by a battery, as in portable phones, the battery being then likely to discharge more rapidly.
Further, it should be noted that the adverse effects of the parasitic transistor are all the more significant as active area 5 is narrow. Given the constant tendency of the semiconductor industry to reduce the sizes of transistors, the adverse effect of the parasitic transistor can only be enhanced, and the transistor can even stop existing if the gate width becomes to small, the resulting transistor being then only formed by the parasitic transistor.
An embodiment of the present invention provides a MOS transistor which avoids the disadvantages of prior art and has a non-impaired voltage threshold.
Another embodiment of the present invention provides a method of forming an active area in a semiconductor substrate enabling obtaining such a structure. The method forms an active area surrounded with an insulating area in a semiconductor substrate, including the steps of:
a) forming in the substrate a trench surrounding an active area;
b) filling the trench with an insulating material to form an edge extending beyond the substrate surface at the periphery of the active area;
c) forming a spacer at the periphery of said edge; and
d) implanting a dopant, whereby the implantation in the area located under the spacer is less deep than in the rest of the active area.
According to an embodiment of the present invention, the spacer has a substantially vertical edge or has a bell shape, the thickness of which thins down as the distance from said edge increases.
According to an embodiment of the present invention, the implantation step is followed by a step of removal of the spacer.
According to an embodiment of the present invention, the step of removal of the spacer is preceded or followed by a step of implantation of another active area with a dopant of another conductivity type than that of the dopant used at step d).
According to an embodiment of the present invention, a step consisting of forming, at the surface of the active area, a protective coating, is provided between the trench filling step and spacer forming step c).
According to an embodiment of the present invention, the protective coating results from the thermal growth of a thin silicon oxide layer at the surface of the substrate.
According to an embodiment of the present invention, the spacer is made of silicon nitride.
According to an embodiment of the present invention, the spacer is made of polysilicon.
An embodiment of the present invention also provides a MOS transistor including a doped channel area adjacent to an insulating area, the dopants present in the portion of the channel area in contact with the insulating layer being closer to the surface than the dopants present in the rest of the channel area.
Another embodiment of the present invention includes an integrated circuit including such a transistor and a terminal including such an integrated circuit.
Many features and advantages of the present invention, will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings.

MOS transistor in an integrated circuit and active area forming method


An intravascular catheter has an outer end portion formed with a discharge orifice. A flexible centering wire supports the outer end portion of the catheter within a blood vessel while a treating agent is delivered into the blood vessel through the discharge orifice. The centering wire, in its natural, free state condition, has a coiled distal end portion. The centering wire is received lengthwise within a channel in the catheter. The centering wire is slidable in the channel from a retracted position to an operative position in which the distal end portion of the wire projects outwardly from the channel through a channel outlet and assumes its natural, coiled condition in contact with the interior wall of the blood vessel to support the outer end portion of the catheter within the blood vessel. The outer end portion of the catheter is centered within the blood vessel, out of contact with the interior wall of the blood vessel.

The present invention is particularly useful in catheters that remain in place within a blood vessel for an extended period of time, such as weeks or months. Such catheters are left in place to nourish patients who cannot be fed by mouth, or, more frequently, to administer chemotherapeutic drugs to treat cancer.
A catheter left on its own within a blood vessel tends to rest its tip against the vessel wall. This causes mechanical irritation of the vessel wall. In addition, the delivery of chemotherapeutic and other drugs against the vessel wall often causes inflammation and eventual thrombosis (clot formation) in the blood vessel. If the catheter tip is close to or in contact with the wall of the blood vessel where the flow is much slower, the undiluted chemicals delivered against the frail endothelial lining of the blood vessel will irritate it and set up local inflammation and thrombosis.
Conversely, if the catheter tip is at the center of the blood vessel, it is positioned at the axis of flow where flow is faster and chemicals delivered by the catheter tip are better mixed with blood and carried away from the wall faster. The chemical agents are also delivered at the greatest distance possible from the walls, that is, at the center of the blood vessel.
What is proposed by this invention is to maintain the catheter on the axis or center of flow in the blood vessel by use of a centering wire. Preferably, the centering wire is a flexible member having in its natural, free state condition a coiled, pigtail-like distal end portion. The centering wire is longitudinally slidable in a channel to an operative position in which the distal end portion projects from a channel outlet and assumes its natural, coiled condition in contact with the interior wall of the blood vessel. Preferably the coil at the distal end extends in an arc of 3600. The coil is sufficiently flexible to expand and contract as needed, depending on the inside diameter of the blood vessel.
One object of this invention is to provide a centering wire for supporting an intravascular catheter in a blood vessel having the foregoing features and capabilities.
Another object is to provide a centering wire for supporting an intravascular catheter within a blood vessel which is durable and long lasting in use, and is capable of being inexpensively manufactured and easily manipulated.
These and other objects, features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying claims and drawings.


The present application provides a catalyst component for alkene polymerization. The catalyst component contains: (a) a group 4 transition metal or rare earth metal, (b) a rigid non-cyclopentadienyl ligand with a tricyclic backbone composed of three ortho-fused 6-membered rings in a linear arrangement (as is the case in xanthene), with or without additional fused rings; the tricyclic backbone contains at least one donor atom within the central ring (as is the case for xanthene, oxanthrene, or acridan); furthermore, donor atoms/groups or aryl rings are attached directly (i.e. via the donor atom in the case of donor groups) to both of the bondable carbon atoms adjacent to at least one of the donor atoms within the central ring (e.g. xanthene with two donor groups, or two aryl rings, or one donor group and one aryl ring adjacent to oxygen), and (c) two or more activatable ligands, such as chloro, alkyl, aryl, allyl or hydride ligands, attached to the central metal if the complex is neutral or anionic, or one or more activatable ligand if the complex is monocationic or dicationic. The rigid non-cyclopentadienyl ligand has a charge of 0, 1- or 2- (considering all donor atoms of the ligand to have an octet of valence electrons). The catalyst component is optionally combined with an activator, typically for the purpose of generating a highly active monocationic or dicationic polymerization catalyst, and the catalyst and/or catalyst components may be in solution, precipitated from solution, or optionally carried on a support.

Synthetic polymers based on one or more alkene monomer such as ethylene, α-olefins, styrenes, dienes and substituted or unsubstituted hydrocarbylacrylates are produced in enormous quantities, and are the most common synthetic materials used world-wide. While many polyalkenes were originally synthesized for commercial use through radical polymerization processes, the development of Ziegler-Natta type polymerization catalysts shifted the focus of research in this area towards the use of metal catalysts. The development of well-defined single-site alkene polymerization catalysts (supported or unsupported) has since become a focus of intense study, with the development of many new polymerization catalysts over the last four decades. These advances, which initially focused primarily on cyclopentadienyl- or metallocene-type catalysts, have provided much greater control over polymer molecular weight, composition and microstructure, and the resulting polyalkenes have applications in a wide range of fields. The discovery that certain catalysts can effect coordination polymerization of a wide range of monomers including styrenes, dienes and methylmethacrylate, in addition to ethylene, also represents a major recent advance.
For alkene polymerization, the regiochemistry of the catalytic process will be determined by the symmetry, steric demands and electronic properties of each catalyst and catalyst component in the present application. For example, atactic, isotactic, syndiotactic and hemiisotactic poly-α-olefins or polystyrenes or poly-1,2-butadienes are typically accessed through the use of appropriate C2v or Cs(achiral), C2, Cs(prochiral), and C1 symmetric catalyst components.
A range of 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene (XA2) thorium and uranium complexes, including cationic alkyl thorium and uranium complexes (see Scheme 1 below) have been disclosed (e.g. Organometallics, 2007, 26, 692-701, Organometallics, 2008, 27, 15-17, Organometallics, 2009, 28, 1891-1899, Dalton Trans. 2010, 39, 6626-6628, Dalton Trans., 2012, 41, 8175-8189, Organometallics, 2013, 32, 1466-1474, and J. Organomet. Chem., 2018, 857, 16-24, and the 2014 Rare Earth Research Conference in Squaw Valley, Calif., June 2014). The cationic trimethylsilylmethyl thorium and uranium complexes display poor or zero ethylene polymerization activity (1 atm ethylene, 25-70° C.) in benzene or toluene. By contrast, these cationic compounds display moderate ethylene polymerization activity (1 atm ethylene, 25-70° C.) in hexanes, fluorobenzene or 1,2-difluorobenzene solvent. This work does not describe non-radioactive catalysts such as rare earth or transition metal complexes.

The complexes [(L1)Ti(NMe2)2], [(L2)Ti(NMe2)2] and [(L2)Ti(CH2Ph)2] {L1=4,5-di(mesitylamido)-2,7-di-tert-butyl-9,9-dimethylxanthene, L2=4,5-di-(cyclohexylamido)-2,7-di-tert-butyl-9,9-dimethylxanthene} were reported. Cationic derivatives or olefin polymerization studies were not described: R. M. Porter, A. A. Danopoulos, Dimethylxan-thene- and dibenzofuran-diamido complexes of titanium, Polyhedron, 2006, 25, 859-863.
Asymmetric allylation of aldehydes and aryl ketones has also been reported using a mixture of Ti(OiPr)4, S-binaphthol and 4,5-bis(triphenylmethylamino)-9,9-dimethylxanthene. However, the resulting in-situ generated catalysts are considered by Maruoka et al. to contain the neutral proligand rather than the 4,5-bis(triphenylmethylamido)-9,9-dimethylxanthene dianion, and this work does not describe cationic complexes or olefin polymerization: H. Hanawa, S. Kii and Keiji Maruoka, New Chiral Bis-Titanium(IV) catalyst with Dibenzofuran Spacer for Catalytic Asymmetric Allylation of Aldehydes and Aryl Ketones, Adv. Synth. Catal., 2001, 343, 57-60.
The patent US 2009/025.9085 A1, SEMI-RIGID LINKED DIAMINES, PRECURSORS THEREFOR, AND TRANSITION METAL DIAMIDO COMPLEXES AS CATALYSTS FOR OLEFIN POLYMERIZATION PROCESSES, by Hagadorn with ExxonMobil describes olefin polymerization catalysts bearing ligands with xanthene and related backbones. The flanking donor atoms (J1, J2, N1 and N2 in the figures below) are not attached directly to the rigid tricyclic backbone and provide a less rigid coordination environment at the metal centre.

The acridan-backbone pro-ligand, 4,5-bis{(diphenylmethylene)amino}-2,7,9,9-tetramethylacridan (H[AIm2]) was synthesized, deprotonation to form lithium 4,5-bis{(diphenylmethylene)amino}-2,7,9,9-tetramethylacridanide (Li[AIm2]; a dimer in the solid state) was reported, and the reactivity of H[AIm2] with [Y(CH2SiMe3)3(THF)2] was described. No stable alkyl derivatives, cationic complexes, or olefin polymerization studies were described: E. W. Y. Wong and D. J. H. Emslie, Cyclometalation and Coupling of a Rigid 4,5-Bis(imino)acridanide Pincer Ligand on Yttrium, Dalton Trans., 2015, 44, 11601-11612.
The extremely sterically hindered pro-ligand, 4,5-bis(2,6-dimesitylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H2[XAT]) was synthesized, and deprotonation to form dipotassium salts was reported: N. R. Andreychuk, D. J. H. Emslie, Potassium-Alkane Interactions within a Rigid Hydrophobic Pocket, Angew. Chem. Int. Ed., 2013, 52, 1696-1699. No transition metal complexes, rare earth complexes, cationic complexes, or polymerization studies have been reported using this ligand.
The pro-ligand, 4,5-bis(2,4,6-triisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H2[XN2]) was prepared, and the synthesis of a dipotassium salt of the XN2 ligand, [(XN2)Ln(CH2SiMe3)(THF)] (Ln=Y or Lu), [(XN2)Y(AlMe4)(THF)], [(XN2)AlMe], [(XN2)LaCl(THF)] and [Li(THF)x][(XN2)La(CH2SiMe3)2] were reported: (i) K. S. A. Motolko and D. J. H. Emslie et al., Yttrium and Aluminum Alkyl Complexes of a Rigid Bis-Anilido NON-Donor Ligand: Synthesis and Hydroamination Catalysis, Organometallics, 2017, 1601-1608, and (ii) K. S. A. Motolko and D. J. H. Emslie et al., Rigid NON-Donor Pincer Ligand Complexes of Lutetium and Lanthanum: Synthesis and Hydroamination Catalysis, RSC Adv., 2017, 7, 27938-27945. The neutral yttrium and lutetium alkyl compounds were tested as ethylene polymerization catalysts but were inactive, and the anionic lanthanum compound was not tested as a polymerization catalyst precursor. No cationic rare earth alkyl complexes were described, and no neutral rare earth complexes with two or more activatable ligands were described.
[(L3)Zr(NMe2)2], [(L3)ZrCl(NMe2)2{Rh(COD)}] and [(L3)ZrCl2(NMe2)2{Rh(COD)}2] (L3=4,5-bis(tert-butylphosphido)-9,9-dimethylxanthene, COD=1,5-cyclooctadiene] have been reported, but no alkyl derivatives, cationic complexes, rare earth complexes, or olefin polymerization studies were described: L. Turculet and R. McDonald, Mono-, Di-, and Trinuclear Complexes Featuring the New Bis(phosphido) Ligand 4,5-Bis(tert-butylphosphido)-9,9-dimethylxanthene ([POP]−2), Organometallics, 2007, 26, 6821-6826.
The pro-ligand, 4,5-bis(2,4,6-triisopropylphenylphosphino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H2[XP2]) was prepared, and the synthesis of dipotassium salts and [(XP2)Yl(THF)2] was reported: K. S. A. Motolko and D. J. H. Emslie et al., Potassium and Yttrium Complexes of a Rigid Bis-Phosphido POP-Donor Ligand, Eur. J. Inorg. Chem., 2017, 2920-2927. However, no group 4 transition metal complexes, alkyl complexes, cationic complexes, or polymerization studies were reported using the XP2 ligand, and no neutral rare earth complexes with two or more activatable ligands were discussed.
The xanthene-backbone pro-ligand 4,5-bis(1-adamantylamino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H2[XAd]) has been prepared and utilized to synthesize alkali metal and thorium(IV) derivatives of the XAd ligand (N. R. Andreychuk, T. Dickie, D. J. H. Emslie and H. A. Jenkins, Dalton Trans., 2018, 4866-4876). No transition metal complexes, rare earth complexes, cationic complexes, or polymerization studies have been reported using the XAd ligand.
A range of late transition metal complexes bearing neutral bis(phosphine) ligands featuring a rigid tricyclic backbone, such as Xantphos and Acriphos shown below, have been published and patented (for e.g. see: (1) P. W. N. M. van Leeuwen, P. C. J. Kamer and J. N. H. Reek, The bite angle makes the catalyst, Pure Appl. Chem., 1999, 71 (8), 1443-1452. (2) M. W. Haenel, S. Hillebrand, Mülheim an der Ruhr (DE), Catalysts Made from Transition Metal Compounds and 4,5-Diphosphinoacridine-Ligands, U.S. Pat. No. 6,290,926 B1). However, these neutral bis(phosphine) ligands would not be well suited for the development of group 4 or rare earth metal polymerization catalysts, and such complexes have not been reported.

Rigid non-cyclopentadienyl group 4 transition metal and rare earth metal catalysts for olefin polymerization


A heating device for a sensor element of a gas sensor, in particular for use in exhaust gas analysis of internal combustion engines, has a heating element, which has an electrical resistor layer. The heating element is electrically insulated from at least one solid electrolyte layer by a layer containing barium and/or strontium and/or calcium. For this purpose, the heating element is embedded in a first insulator, which is adjoined by a second insulator. The first insulator has a higher barium and/or strontium and/or calcium content (expressed in weight percentage) than the second insulator.

Such a heating device is known, for example, from German Published Patent Application No. 198 34 276 for heating a sensor element which is used in a gas sensor for exhaust gas analysis in internal combustion engines. The sensor element has solid electrolyte layers and electrodes, as well as a heating device having a stratified design. The heating device is situated on a solid electrolyte layer or between one solid electrolyte layer and another solid electrolyte layer. The heating device contains a heating element made up, for example, of an electrical resistor layer and an insulator in which the heating element is embedded. The insulator is essentially made of aluminum oxide. The insulator electrically insulates the heating element against the solid electrolyte layers and the electrodes, as well as against electron and ion conduction, so that the function of the sensor element is not impaired by the operation of the heating device.
The heating device is manufactured by applying a lower insulator layer, the heating element, and an upper insulator layer to a green foil, i.e., an unsintered ceramic foil, using thin layer or thick layer technology. The green foil including the printed-on heating device is subsequently laminated together with other green foils onto which electrodes may be printed, for example, and is sintered.
The insulator is often porous. The porosity of the insulator is achieved by adding a pore former prior to sintering. During sintering, the pore former is burned away, so that a porous structure is obtained. The porosity is adjusted via the amount of pore former, for example, carbon glass, which is added.
German Published Patent Application No. 198 53 601 furthermore describes a broadband lambda probe for determining the oxygen concentration in exhaust gases of internal combustion engines. The sensor element of the probe includes a heating device, which is electrically insulated from a solid electrolyte layer by an insulator. The insulator contains a mixture of aluminum oxide, barium oxide, and/or strontium oxide to prevent leak currents.
The disadvantage of such a sensor element is that the sintering characteristics, in particular sintering shrinkage, of the solid electrolyte layer and the adjacent barium and/or strontium-containing insulator are distinctly different. The thermal expansion coefficients of the insulator and the solid electrolyte layer are also different. The poor bonding of the insulator to the solid electrolyte layer results in cracks, for example, in the event of rapid temperature changes, which impair the functionality of the sensor element.


A gait generation for a biped mobile robot having a body and two legs each connected to the body and having a foot at its distal end in walking a terrain including a first surface and a second surface met at a dihedral angle such that the robot feet are in simultaneous contact with the different two surfaces. The centers of ground contact pressure distribution of the first and second surfaces are determined. A virtual third surface which assumes to vary from the first surface to the second surface is established. Then a virtual ZMP (Zero Moment Point) is assumed on the virtual third surface such that the virtual ZMP is displaced along a path obtained by connecting the centers of the ground pressure distribution of the first and second surfaces. And a gait for the robot is generated such that a ZMP kinematically determined from the motion of the robot coincides with the target ZMP.

1. Field of the Invention
This invention relates to a system for generating a gait (walking pattern) for a legged mobile robot, more particularly to a system for generating a gait (walking pattern) for a legged mobile robot using biped locomotion, which enables the robot to satisfy the conditions for dynamic equilibrium and achieve stable walking even when walking on uneven terrain not constituted by a single plane.
2. Description of the Prior Art
Legged mobile robots, in particular legged mobile robots using biped locomotion, are taught by Japanese Laid-open Patent Publication Nos. 62 (1987)-97005 and 63(1988)-150176. An in-depth discussion of robot control, including the control of legged mobile robots, can be found in Robotics Handbook, Robotic Society of Japan, Oct. 20, 1990.
As explained in detail starting from page 347 of the Robotics Handbook, the concept of ZMP (zero moment point) has been introduced into the control of legged mobile robots, and the control is conducted by determining the gait (walking pattern) such that the ZMP follows a target trajectory. Here, the term ZMP means a point on the ground at which the horizontal moments around the x and y axes produced by the ground reaction force is zero irrespective of whether or not the vertical moment around the z axis arises. A required condition for dynamic force equilibrium in this case is that the ZMP be located inside a minimum convex polygon including the ground surface. Moreover, the margin of stability of the gait (walking pattern) can be optimized by designing it such that the ZMP is positioned as close as possible to the center of the minimum convex polygon including the ground surface.
The ZMP is, however, a concept that holds only with respect to a single plane, more specifically, a single horizontal plane. The ZMP concept cannot be applied to the design of a gait for a robot which is to walk across uneven terrain such as inclined terrain of varying gradient or the like because under such circumstances the robot will sometimes be in simultaneous contact with two or more ground planes that differ in height or the direction of their normals.

Gait generation system for a legged mobile robot


A TFT array having a plurality of gate lines and a plurality of drain lines formed on a transparent substrate. The gate lines intersect with the drain lines. TFT are formed at the intersections of the gate lines and the drain lines. An insulating film is formed on the drain lines and the drain electrodes of the TFTs. Pixel electrodes are formed, each overlapping the corresponding gate line and the corresponding drain line. The pixel electrode has a large area and thus, have a high opening ratio. The TFT array can, therefore, help to provide a liquid crystal display having high contrast.

1. Field of the Invention
The present invention relates to a TFT (Thin Film Transistor) array having a plurality of TFTs arranged in the form of a matrix, and each having a pixel electrode and made by stacking a gate electrode, a semiconductor layer, a source electrode, a drain electrode, and the like, on a transparent insulation substrate.
2. Description of the Related Art
Conventional TFTs as switching elements are disclosed in Published Examined Japanese Utility Model No. 44-5572 (U.S. Ser. No. 132,095), Published Examined Japanese Patent Application No. 41-8172 (U.S. Ser. No. 344,921), and P.K. Weimer, "The TFT--A New Thin-Film Transistor", PROCEEDlNGS OF THE IRE, June, 1962. Liquid crystal display panels using such TFTs are disclosed in "A 6.times.6 Inch 20 lines-Per-Inch Liquid Crystal Display Panel", IEEE Transactions on Electron Device, vol. ED-20, No. 11, Nov. 1973 and U.S. Pat. No. 3,840,695.
On the other hand, U.S. Pat. Nos. 3,765,747 and 3,862,360, and Published Unexamined Japanese Patent Application Nos. 55-32026, 57-20778, and 58-21784 disclose a technique wherein a MOS transistor is formed on a monocrystalline semiconductor substrate, and the resultant structure is used as one of the substrates of a liquid crystal display panel. However, if liquid crystal panels are constituted by these semiconductor substrates, only reflection type displays can be obtained. In addition, the manufacturing process of such panels are as complex as that of LSIs. Moreover, it Is difficult to obtain a large display panel.
The above-described active matrix liquid crystal panels, therefore, has TFTs used as switching elements. The structures of these TFTs can be classifield into a coplanar type, an inverted coplanar type, a staggered type, and an inverted staggered type, as disclosed in the article by P.K. Weimer. Of these types, the inverted staggered type TFT can be formed by stacking a plurality of thin films successively in a vacuum. For this reason, the number of manufacturing steps is substantially decreased. As a result, the characteristics of a product are stabilized, and the rate of occurrence of defective transistors is decreased.
FIGS. 1 and 2 show structures of the above-described inverted staggered type TFT and a TFT array obtained by arranging a plurality of such inverted staggered type TFTs on an insulating substrate. Referring to FIGS. 1 and 2, a plurality of TFTs 1 are arranged on a transparent insulating substrate 2 in the form of a matrix. Gate electrodes 3 of TFTs 1 are connected by a gate line 4 extending in the row direction. Drain electrodes 5 of TFTs 1 are connected by a drain line 6 extending in the column direction. A source electrode 7 of each TFT 1 is connected to a transparent electrode 8 independently formed in an area surrounded by the gate and drain lines 4 and 6 (an electrode, to which a data signal is supplied, will be referred to as a drain electrode hereinafter). More specifically, as shown in FIG. 2, the gate electrode 3 consisting of Cr or the like is formed on the transparent glass substrate 2, and a gate insulating film 9 consisting of silicon oxide or silicon nitride is formed on the upper surface of the glass substrate 2 including the upper surface of the gate electrode 3. A semiconductor film 10 consisting of amorphous silicon is stacked on the gate insulating film 9 above the gate electrode 3. Drain and source electrodes 5 and 7 are formed on the semiconductor film 10. They are separated from each other by a predetermined distance, forming channel portion 11. Drain and source electrodes 5 and 7 respectively have contact layers 5a and 7a, and metal layers 5b and 7b, and are electrically connected to the semiconductor 10. The source electrode 7 is connected to the transparent electrode 8 consisting of Indium-Tin-Oxide (to be referred to as an ITO hereinafter).
In the TFT used for the above-described TFT array, since part of the drain electrode 5, the drain line 6, and the transparent electrode 8 are formed on the gate insulating film 9, both the electrodes tend to be short-circuited, and hence the rate of occurrence of defects becomes high. Especially in the TFT array using this TFT, since the transparent electrode 8 is formed in a region surrounded by the gate and drain lines 4 and 6, short-circuiting tends to occur between the transparent electrode 8 and the drain line 6.
In order to prevent such short-circuiting, predetermined distance L determined by process and alignment precision in formation of the transparent electrode 8 and the drain line 6 is formed therebetween. Distance L is usually as along as 20 .mu.m, or more. Although the long distance L can prevent the above-described short-circuiting, the area of the transparent electrode 8 is reduced. That is, the problem of reduction in effective display area is posed. For example, the opening ratio, i.e., the ratio of the area of the transparent electrode 8 to an area for arranging one TFT and one transparent electrode on the glass substrate 2 becomes as small as about 50% even if distance L is reduced to a minimum of 20 .mu.m.


The present invention relates to a device and a method for coordinating an APS operation and a recovery operation. The device includes a working channel detection unit, a protection channel detection unit, a protection protocol unit and a recovery protocol unit. The method comprises: when the working channel of current service fails, the working channel detection unit reporting a working channel alarm to the protection protocol unit and a recovery protocol unit of current node; the recovery protocol unit starting up a timer after receiving the working channel alarm, and the protection protocol unit determining whether the recovery operation needs to be started up immediately after receiving the working channel alarm, and if yes, the protection protocol unit notifying the recovery protocol unit to start up the recovery operation immediately; the recovery protocol unit starting up the recovery operation immediately after receiving the notification. The present invention reduces the damage time of the service in the case of the APS function failure.

With the increased expansion of network scale and demands for high-quality services, at present, the optical network has higher and higher demands for network survivability. The network survivability refers to that the network can still preserve acceptable service quality grade in the case of failures. The APS operations and the recovery operations are main means for improving optical network survivability and supporting the demands for QoS (Quality of Service) of service transfer.
The basic idea of the APS operations is to pre-configure a protection channel for services. In the case of fault occurring in the working channel, the working channel detection unit of corresponding node detects an alarm and reports it to the protection protocol unit of the present node; the protection protocol unit starts up an APS operation after receiving the working channel alarm, that is, the protection protocol unit runs the configured protection protocol algorithm and also exchanges signals with protection protocol units of other nodes in the protection channel; then the protection protocol unit of each node in the protection channel sends an switching instruction to the execution units of the present node respectively; finally, the execution units of each node in the protection channel execute the APS operation and switch the service over to the protection channel to ensure the normal operation of services. APS operations bring about the advantages of rapid switching and short service interruption time, but the network resources utilization rate is relatively low.
The recovery operations do not pre-configure protection channel for services. In the case of fault occurring in the working channel, the working channel detection unit of corresponding node detects an alarm and reports it to the recovery protocol unit of the present node; the recovery protocol unit starts up the recovery operation after receiving the working channel alarm, that is, this recovery protocol unit recalculates a new channel for services in the idle resources of current network, and also exchanges signals with recovery protocol units of other nodes in the new channel; then the recovery protocol unit of each node in the new channel sends a switching instruction to the execution units of the present node respectively; finally, the execution units of each node in the new channel execute recovery operation and switch services over to the new channel to ensure the normal operation of services. The recovery operation has a relatively high utilization rate of network resources, but it requires real-time computation of service channel and thus the service fault time is relatively long.
As for the service requiring higher QoS, the service is often provided with APS functions and recovery functions. As illustrated in FIG. 1, the device comprises a working channel detection unit, a protection protocol unit and a recovery protocol unit, wherein when the working channel detection unit detects a working channel alarm, it reports the alarm to the protection protocol unit and the recovery protocol unit; the protection protocol unit starts up an APS operation immediately after receiving the working channel alarm, while the recovery protocol unit waits for a pre-set time period (holdoff) after receiving the working channel alarm and then checks whether the working channel detection unit still detects an alarm or not, wherein if yes, it starts up the recovery operation, otherwise the recovery operation needs not to be started up because the service operation is normal. Due to lack of signaling interaction between the protection protocol unit and the recovery protocol unit, in the case of the APS function failure, e.g. when the working channel and protection channel of the service both fail and the recovery operation shall be started up immediately, the recovery protocol unit can not start up the recovery operation until waiting for the time of period (holdoff), such that the service fault time is increased by the time of holdoff, which increases service interruption time.

Device and method for coordinating automatic protection switching operation and recovery operation


A vehicular communication apparatus communicably connected to a portable communication terminal, includes: an information acquisition device that acquires facility information about a facility from the portable communication terminal; an information storage device that controls a storage to store the facility information in association with the portable communication terminal; and an information display device that controls a display to display the facility information stored in the storage when the portable communication terminal providing the facility information is reconnected to the vehicular communication apparatus, and that controls the display not to display the facility information stored in the storage when a new portable communication terminal different from the portable communication terminal providing the facility information is connected to the vehicular communication apparatus.

According to a recent technology (e.g., see patent document 1), a vehicle is mounted with a communication apparatus having the short range communication function. The communication apparatus wiredly or wirelessly connects with a portable communication terminal (e.g., mobile telephone). Various information stored in the portable communication terminal is transmitted to the communication apparatus on the vehicle. The information transmitted from the portable communication terminal to the vehicular communication apparatus includes POI (Point Of Interface) information about various facilities, for example. The information can be used as a destination or a route point configured for route guidance of a navigation system, for example.
Patent Document 1: JP-A-2004-248042
As mentioned above, the information transmitted from the portable communication terminal to the vehicular communication apparatus is stored in the portable communication terminal. The information depends on preferences and behavioral patterns attributed to an owner of the portable communication terminal. The information can be also considered to be private information. There is a demand for preventing another person from accessing the private information, that is, the information transmitted from the owner's portable communication terminal to the vehicular communication apparatus.

Vehicular communication apparatus and vehicular communication system


Methods and systems for automatic detection of Atrial Fibrillation (AF) are disclosed. The methods and systems use time-varying coherence functions (TVCF) to detect AF. The TVCF is estimated by the multiplication of two time-varying transfer functions (TVTFs).

Atrial fibrillation is the most common sustained dysrhythmia worldwide. Over 2.3 million Americans are currently diagnosed, and the prevalence of AF is increasing with the aging of the U.S. population. Through its association with increased risk for heart failure, stroke and mortality, AF has a profound impact on the longevity and quality of life of a growing number of people. Although new AF treatment strategies have emerged over the last decade, a major challenge facing clinicians and researchers is the paroxysmal nature of AF, which makes it difficult to detect because it is short lasting, often asymptomatic, and intermittent. Thus, there is a pressing need to develop methods for accurate AF detection including paroxysmal rhythms. Such a method would have important clinical applications for pre- and post-treatment detection of AF. For these reasons, the importance of developing new AF detection technologies has been emphasized.
Many algorithms have been developed to detect AF and can be categorized as being based on 1) P-wave detection or 2) RR interval (RRI) variability. AF detection based on P-wave absence has not gained wide acceptance because determination of the P-wave fiducial point localization is challenging, especially for Holter monitoring applications. Indeed, for Holter monitoring, it is difficult to find uncontaminated RR intervals due to motion and noise artifacts which can confound the accuracy of P-wave detection. Subsequently, many studies have used variability of RR interval time series instead. Specifically, the aim is to quantify markedly increased beat-to-beat variability RR interval time series in AF. Consequently, most algorithms show higher sensitivity and specificity values than the methods that screen for the absence of P-waves. However, most of these RR intervals methods are based on comparing the density histogram of the data segment with previously-compiled standard density histograms of RR segments during AF using the Kolmogorov-Smirnov test. The main disadvantage of this approach is that it requires storage of large amounts of histogram data and threshold values of various characteristics of AF.
Accordingly, there is a need for improved methods and systems for detecting atrial fibrillation.

Methods and systems for atrial fibrillation detection


Provided are a stainless steel for a proton-exchange membrane fuel cell separator having high durability and a low contact resistance (i.e., high electrical conductivity) and a proton-exchange membrane fuel cell using the same. More specifically, a stainless steel for a proton-exchange membrane fuel cell separator has a composition comprising 0.03% mass % or less of C, 16-45 mass % of Cr, 0.03 mass % or less of N, 0.1-5.0 mass % of Mo, wherein a total of the C content and the N content satisfies 0.03 mass % or less; a balance portion is comprised of Fe and unavoidable impurities; an atomic ratio of Cr/Fe with respect to Al, Cr, and Fe contained in a passive film on a surface of the stainless steel is 1 or greater.

In recent years, from the viewpoint of the global environmental conservation, the development has been progressed for fuel cells of the type that has high electric power generation efficiency and that do not emitting CO2. Fuel cells of this type generate electricity by causing the reaction between H2 and O2. Depending on the type of electrolyte, the fuel cells under development are classified by the type of electrolyte into, for example, phosphoric acid type fuel cells, molten carbonate fuel cells, solid oxide fuel cells, alkaline type fuel cells, and proton-exchange membrane fuel cells.
Of these cells, compared with other fuel cells, a proton-exchange membrane fuel cell has the following advantages:
(a) The fuel cell has an electric power generation temperature of 80° C.; that is the cell is capable of generating electricity at a significantly low temperature;
(b) The mainbody of the fuel cell can be formed to be light and compact; and
(c) The fuel cell can start up in a short time.
The proton-exchange membrane fuel cell is, therefore, one of today's most attractive fuel cells that are appreciated for use as electric vehicle on-board power sources, home-use stationary power generators, and portable compact power generators.
A proton-exchange membrane fuel cell of this type generates electricity from hydrogen and oxygen through polymer membranes. As shown in FIG. 1, the cell is structured such that a membrane-electrode assembly 1 is clamped between gas diffusion layers 2 and 3 (carbon paper, for example) and further between separators 4 and 5 to form to be a single constitutional element (so-called a "unit cell"), wherein electricity force is generated between the separators 4 and 5.
The membrane-electrode assembly 1 is called "MEA (or, membrane-electrode assembly) that is formed by integration of a polymer membrane and an electrode material such as a carbon black carrying a platinum-based catalyst on obverse and reverse surfaces thereof and have a thickness of from several tens of micrometers (μm) to several hundreds of micrometers (μm). Many alternative cases can be seen where the gas diffusion layers 2 and 3 are integrated with the membrane-electrode assembly 1.
In the case of adaptation of such the proton-exchange membrane fuel cell for the use as described above, the fuel cell is used in the form of a fuel cell stack that is formed by series connecting several tens to several hundreds of unit cells as described above.
The separator 4, 5 is required to have functionalities as
(A) A barrier wall to play the role of separating between unit cells;
(B) A conductor for carrying generated electrons;
(C) An airflow channel or hydrogen flow channel along which O2 (i.e., air) or H2 flows; and
(D) A discharge channel along which generated water, gas and the like flows.
Further, for the separators 4 and 5, separators having high properties such as high durability and electrical conductivity are required to be used for practical using of the proton-exchange membrane fuel cell.
Regarding the durability (i.e., output voltage fall withstanding property), when used as an electric-vehicle on-board power source, the fuel cell is contemplated to have a durability time of about 5000 hours. As an alternative case where the fuel cell is used as, for example, a home-use stationary power generator, the durability time is contemplated to have about 40000 hours. As such, the separator 4, 5 is required to have properties such as corrosion resistance sufficient to be durable against the long-time power generation.
Regarding the electrical conductivity, the contact resistance between the separator 4, 5 and the gas diffusion layer 2, 3 is desired to be as low as possible. A reason is that an increase of the contact resistance between the separator 4, 5 and the gas diffusion layer 2, 3 causes a reduction of the electric power generation efficiency of the proton-exchange membrane fuel cell. That is, as the contact resistance is lower, the electrical conductivity is higher.
Hitherto, a proton-exchange membrane fuel cell using graphite for a separator 4, 5 has been put into practical use. The separator 4, 5 formed of the graphite has advantages of having a relatively low contact resistance and not causing corrosion. On the other hand, however, the separator is easily damaged by shock. In addition, the separator has a disadvantage of increasing the processing costs for forming airflow channels 6 and hydrogen channels 7. These disadvantages of the separator 4, 5 formed of the graphite causes disturbance against popularization of proton-exchange membrane fuel cells.
As such, attempts have been made to apply metallic materials in lieu of the graphite as the material of the separator 4, 5. Particularly, various studies and approaches have been made to implement practical use of separators 4, 5 using stainless steels as materials.
For example, Japanese Unexamined Patent Application Publication No. 8-180883 discloses a technique using metal, such as stainless steel that readily forms a passive film. However, the formation of the passive film causes an increase in the contact resistance, leading to a decrease in the electric power generation efficiency. As such, problems have been pointed out regarding the matters in which the metallic materials have, for example, high contact resistances and low corrosion resistance in comparison with carbon materials such as graphite.
In addition, attempts have been made such that stainless steels not subjected to surface treatment are used as they are for separators. For example, Japanese Unexamined Patent Application Publications No. 2000-239806 and No. 2000-294256 each discloses a separator-use ferritic stainless steel formed such that Cu and Ni are positively added, impurity elements such as S, P, and N are then reduced, and C+N≦0.03 mass % and 10.5 mass %≦Cr+3×Mo≦43 mass % are satisfied. In addition, Japanese Unexamined Patent Application Publications No. 2000-265248 and No. 2000-294256 each discloses a separator-use ferritic stainless steel formed such that Cu and Ni are restricted to 0.2 mass % or less thereby to inhibit dissolution of metallic ions, impurity elements such as S, P, and N are then reduced, and C+N≦0.03 mass % and 10.5 mass %≦Cr+3×Mo≦43 mass % are satisfied.
Any of the inventions described above is based on the following idea. The composition of the stainless steel are controlled to the predetermined range to strengthen the passive film, whereby the stainless steel is not subjected to the surface treatment and is used as it is for reducing deterioration due to dissolved metallic ions in the catalytic activity of the electrode-carrying catalyst, thereby to restrain the increase in contact resistance with the electrode due to corrosion products. Thus, the stainless steel is not of the type that reduces the contact resistance itself of the stainless steel. Neither is a stainless steel of the type that enables securing the durability (i.e., output-voltage withstanding property) sufficient to withstand electric power generation over several tens of thousands of hours.
In addition, Japanese Unexamined Patent Application Publication No. 10-228914 discloses techniques enabling securing of high output in the manner that gold plating is applied to the surface of separators of, for example, a SUS 304 metallic material, thereby to reduce the contact resistance. However, with thin gold plating being performed, it is difficult prevent pinholes; and in contrast, with thick gold plating being performed, there remains a cost problem pending resolution.
Further, Japanese Unexamined Patent Application Publication No. 2000-277133 discloses techniques of obtaining separators improved in electrical conductivity in the manner that carbon powder is dispersed on a ferritic stainless steel base material. However, also in the case of using such powder, the surface treatment of the separator requires corresponding costs, still remaining cost problems pending resolution. In addition, a problem is pointed out in that in an event where the surface-treated separator is, for example, damaged during assembly, the corrosion resistance thereof decreases significantly.
Japanese Unexamined Patent Application Publication No. 2003-223904 discloses results of research and investigation of the influence of surface roughness of the surface of stainless steel. In this case, the stainless steel surface roughness is set as: Ra: 0.01 μm to 1 μm; and Ry: 0.01 to 20 μm. However, the contact resistance was found insufficient from the viewpoint of securing higher cell output.
In view of the above-described problems with the conventional techniques, it could be helpful to provide a stainless steel for a proton-exchange membrane fuel cell separator that has a high corrosion resistance and a low contact resistance (i.e., high electrical conductivity) and to provide a proton-exchange membrane fuel cell using the same.
More specifically, it could be helpful to provide a stainless steel for a proton-exchange membrane fuel cell separator and a proton-exchange membrane fuel cell using the same, wherein the proton-exchange membrane fuel cell separator is provided by specifying not only composition of stainless steel being as base material, but also composition of a passive film existing on the surface thereof, thereby to have a low contact resistance, a high electric power generation efficiency, and a high corrosion resistance of the stainless steel itself even without being subjected to a surface treatment.

Stainless steel for solid polymer fuel cell separator and solid polymer typefuel cell using the stainless steel


A torque limiter comprises a first body, a second body, and a biasing mechanism. The second body is rotationally attached relative to the first body. The biasing mechanism comprises at least first and second compression springs and an adjustment device. The first spring has a maximum compression condition. The first and second springs are configured and adapted to create a torque-threshold below which the second body cannot be rotated relative to the first body and above which it can. The torque-threshold is adjustable via the adjustment device throughout a first torque range and a non-overlapping second torque range. The biasing mechanism is configured and adapted such that the first spring progressively compresses as the torque-threshold increases throughout the first torque range, and such that throughout the second torque range the first spring is in its maximum compression condition and the second spring progressively compresses as the torque-threshold increases.

1. Field of the Invention
This invention pertains to a torque limiter. More specifically the present invention pertains to a torque limiter having multiple compression springs. The torque limiter prevents torque above an adjustable torque-threshold from being transferred between two bodies of the device.
2. General Background
Torque limiters are used for a variety of purposes. One such purpose is to prevent damage to one or more components of an assembly by limiting how much torque can be transmitted from one component to another. By connecting the two components to each other via a torque limiter, only torque below a set torque-threshold of the torque limiter can be transferred through the torque limiter. For example, the first component could be a valve handle and the second component could be the shaft of a valve gate. By connecting the handle to a torque limiter, excessively high torque cannot be applied to the shaft of a valve gate by turning the valve handle.
One common type of torque limiter is a ball detent torque limiter. A ball detent torque limiter comprises a plurality of ball bearings that are spring biased into a plurality of detents. An excessively high torque will cause the balls to counteract the spring bias and move out of the detents. When the balls are out of the detents, the torque limiter generally becomes incapable of transferring torque (i.e., rotational slippage occurs). By adjusting the biasing force of the springs, the torque-threshold (i.e., the torque above which rotational slippage occurs) can be adjusted. Because of their compact size, ball detent torque limiters often use Belleville compression springs to generate the biasing forces. Nonetheless, most torque limiters have a relatively limited range over which the torque-threshold can be set or have cumbersome means for adjusting the torque-threshold.

Torque limiter and method of limiting torque transfer


According to an embodiment, an information processing apparatus includes an attribute determiner and a setter. Each of acquired first sets indicates a combination of observation information indicating a result of observation of an area surrounding a moving body and position information. The attribute determiner is configured to determine, based on the observation information, an attribute of each of areas into which the area surrounding the moving body is divided, and to generate second sets, each indicating a combination of attribute information indicating the attribute of each area and the position information. The setter is configured to set, based on the second sets, reliability of the attribute of the area of a target second set, from correlation between the attribute of the area of the target second set and the attribute of corresponding areas each indicating the area corresponding to the target area in the areas of the other second sets.

In relation to semantic segmentation technology to identify an attribute for each of a plurality of pixels included in an image obtained through imaging by a camera, a method to calculate a probability (reliability) of an identification result of the attribute is known.
For example, in a convolution neural network, a technology to generate a large number of attribute identification results from one input image by sampling and removing a unit at the time of a test, obtain an average value of the attribute identification results as an attribute, and output a dispersion value as the reliability of the attribute is known.
However, the above-described conventional technology has problems that an amount of processing is large because the attribute identification by removal (dropout) of a network unit is conducted a plurality of times for one input image, and obtainment of sufficient accuracy is difficult because the reliability is calculated using only one image.

Information processing apparatus and information processing method using correlation between attributes


A digital temperature sensor and a system and a method for measuring a temperature are provided. The system includes a reference signal generator including one or more resistance elements; a temperature sensor including a plurality of discrete resistance elements arranged parallel with one another; a multiplexer multiplexing the plurality of discrete resistance elements and the reference resistance element so that the plurality of discrete resistance elements sequentially distribute a power voltage together with the reference resistance element; a comparator having the voltages distributed by the reference resistance element and a discrete resistance element selected by the multiplexer; and a counter counting sequential switchings of the multiplexer. The counter information of the output level transit time of the comparator is provided to the controller, and the system obtains temperature information according to temperature change information from turn information of the discrete resistance elements according to the counter information.

1. Field of the Invention
The present invention relates generally to a digital temperature sensor. More particularly, the present invention relates to a digital temperature sensor digitally displaying a temperature measured depending on a slight variation in a resistance value without using an analog-to-digital converter, and a system and a method for measuring a temperature using the digital temperature sensor.
2. Description of the Related Art
Temperature sensors are widely used in various industry fields. For example, temperature sensors are used to precisely produce products in precision industries, such as the semiconductor industry, as well as to control a temperature in electric home appliances such as air conditioners, refrigerators, or the like.
Currently used thermometers are classified according to the following measurement principles.
There are thermometers which use thermal expansion, for example, gas thermometers, liquid thermometers, and bimetal thermometers. The liquid thermometers include thermometers using mercury or kerosene. In the past, most alcohol thermometers (using alcohol dyed red) have red liquid columns. However, condensation easily occurs in an upper space of the liquid column, which generates an error in an indicator. Thus, the liquid thermometers have used kerosene for the past 30 years. Liquid thermometers include home thermometers clinical thermometers, maximum-minimum thermometers and Beckman's thermometers. The bimetal thermometers use bimetal made by adhering two types of metal plates having different expansion coefficients, i.e., copper and nickel thin plates. In the bimetal thermometers, the expansion coefficient of the copper is greater than that of the nickel. Thus, when a temperature is high, the nickel plate is bent. When the temperature is low, the copper plate is bent. The bimetal thermometers display the temperature using this principle.
There are thermal resistance thermometers using temperature variations in an electric resistance. The thermal resistance thermometers include resistance thermometers using a property that electric resistance values of metal and semiconductor depend on a temperature.
In thermocouple thermometers, both ends of two types of metals or alloy wires contact to make a loop-shaped circuit through which electricity flows. If a temperature difference is given to the contacting ends, a thermoelectromotive force is generated at the contacting ends, and thus a current flows in the contacting ends. This is called Peltier effect (thermoelectric effect). The thermocouple thermometers utilize the Peltier effect. Potentiometers or millivoltmeters having great internal resistances measure the thermoelectromotive force and are widely used for measuring a temperature during compensation of the temperature and the thermoelectromotive force. This is because of a small error in heat capacity and a superior response to heat due to the very small volume of a metal junction that senses humidity. Examples of a thermocouple include a couple of platinum wire and alloy wire of platinum and rhodium, a couple of copper wire and constantan wire, and the like.
There are color thermometers depending on light. Examples of the color thermometers include optical pyrometers and radiation pyrometers. The optical pyrometers compare color temperatures of objects to be measured with a standard color temperature to measure a temperature, i.e., may measure a color temperature between 700° C. and 2500° C. In the radiation pyrometers, thermal energy radiated from an object to be measured is condensed using a lens or a concave mirror and a thermistor (a resistor sensitive to a room temperature) is put on a focus to measure a temperature depending on variations of a resistance value caused by a rise in the temperature of thermistor. An example of the radiation pyrometers includes thermography thermometers using a semiconductor thermosensitive device for infrared rays. A distribution of a surface temperature of the earth or the skin temperature of the human body is investigated from an artificial satellite using the thermography thermometer.
There are segercone thermometers and thermocolor thermometers. The segercone thermometers are about-10-cm-triangle cones made by kneading silicate and metal oxide. The segercone thermometers are used to investigate temperature distribution in a furnace by disposing and heating triangle cones and observing a melting degree of the triangle cones. The thermocolor thermometers use a principle of a change in a color of a thermocolor called heat sensitive paint. The thermocolor thermometers use a phenomenon of a reversible change in a color of complex salt such as cobalt, chrome, or the like depending on temperature. The complex salt is kneaded with clay and then dried to make thermoclay. Liquid crystal thermometers using a temperature characteristic of a liquid crystal are recently released as the thermocolor thermometers.
The thermal resistance thermometers use a property that an electric resistance of a conductor varies with variations in temperature, i.e., a property that a corresponding temperature can be measured using a variation rate of a resistance with respect to variations in unit temperature. The variation rate of resistance with respect to the unit temperature is called a temperature coefficient of resistance (TCR). If a resistance value is increased with an increase in temperature, the variation rate of resistance is called a positive TCR. If the resistance value is reduced, the variation rate of resistance is called a negative TCR. A metallic material used for measuring a temperature mainly has a positive TCR. Examples of the metallic material include platinum, nickel, copper, and the like. As a material is pure, a TCR of the material is increased and constant. William Siemens first manufactured a resistance thermometer using platinum to measure a temperature in 1871. As previously described, resistance values of all kinds of metals depend on temperature as shown in Table 1 below.
TABLE 1MaterialResistance (uΩm)TCR (ppm/° C.)Carbon (graphite)1,390−500Manganin (alloy)48.22Nichrome1011,700Chromium12.93,000Aluminum2.833,600Silver1.633,800Copper1.723,900Platinum10.63,927Tungsten4.204,500Iron9.716,510Nickel6.846,900Gold2.408,300
Sensors made of a metal such as nickel, copper, platinum, or the like and an alloy have been developed using a dependence of a resistance value of a metal on temperature as shown in Table 1. However, platinum is mainly used due to its superior stability and good TCR. A platinum temperature sensor is used as a standard temperature sensor in a temperature area between −260° C. and 630° C. due to its high accuracy.
FIG. 1 is a block diagram of a conventional digital temperature measuring system using a platinum resistance. The conventional digital temperature measuring system includes stationary and variable resistors R0 and R(T) connected to each other in serial, a direct current (DC) offset removing circuit 10, an amplifier 20, an analog-to-digital converter (ADC) 30, a digital display 40, and a controller 50.
The stationary resistor is set so that its resistance value R0 is kept at a reference temperature T0, mainly at a room temperature of 20° C., and the variable resistor is set so that its resistance value R(T) varies with a temperature. The resistance value R(T) of the variable resistor at a temperature T° C. can be expressed as in Equation 1:R(T)=R0[1+α(T−T0)]  [Equation 1]where R(T) denotes a loadless resistance value Ω of the variable resistor at the temperature T° C., R0 denotes a loadless resistance value Ω of the variable resistor at the reference temperature T0, α denotes a TCR ppm/° C. or ppm/K, T denotes a substantially measured temperature ° C. or K of the variable resistor, and T0 denotes the reference temperature ° C. or K.
For example, if a platinum resistor having a TCR α of 3900 ppm/° C. and a resistance value of 1 kΩ at a room temperature is used as a temperature sensor, it is supposed that a voltage of 1V is applied to both ends of the platinum resistor at a power voltage VDD of 2V and the temperature is increased by 1° C. According to Equation 1, R(21° C.)=1 kΩ[1+0.0039]=1.0039 kΩ. In other words, as shown in FIG. 2, the platinum temperature sensor has a resistance of 1 kΩ at a temperature of 20° C. However, a resistance component of 39Ω is added to the resistance value of 1 kΩ at a temperature of 21° C. Thus, the controller 50 controls the digital display 40 to display a temperature of 20° C. when the voltage of 1 V is output but to display a temperature of 21° C. when a voltage of about 1.0019V is output due to a change of the resistance value of the platinum temperature sensor to 1.0039 kΩ.
Such a digital temperature measuring system displays a temperature based on variations in an output voltage caused by variations in a resistance value of a platinum resistor. However, in the digital temperature measuring system, a signal variation in an output voltage caused by variations in the resistance value of the temperature sensor is slight. Thus, the probability that an error occurs is very high. Also, the digital temperature measuring system requires a low noise circuit and a high-performance amplifier for removing DC offset prior to ADC conversion.

Digital temperature sensor, and system and method for measuring temperature


Provided is a motor control device controlling several motors independently. The motor control device includes a plurality of inverters supplying power to each of several motors, respectively, and a control CPU provided with a command generator generating a control command, a PI controller that generates a torque command and a speed command by performing a proportional integral operation using feedback information and the control command transmitted from the command generator, and a vector controller that generates a PWM control signal using the torque command and the speed command and supplies the generated PWM signal to the plurality of inverters, in which the command generator includes an input translator that converts the command input as a QMCL command into the control command.

A motor is a device that generates torque by using electromagnetic induction law and widely used as a driving means in most industrial fields such as robots, electric vehicles, industrial machines, and household applications.
The performance of a motor is generally divided into rotation speed and torque, and a motor controller is used to control the rotation speed and/or the torque in real time when operation speed of the device and/or the load are not constant.
A control method of the motor controller is divided into a variable voltage variable frequency (VVVF) control, a sensorless vector control, and a sensor feedback vector control, etc. In the fields requiring precise control such as robots, electric vehicles, and precision machines, the sensor feedback vector control has been generally applied.
The motor controller is generally used for each motor, and even in a device using several motors such as a multi-axis machine and a multi-axis robot, in many cases, a separate motor controller is connected to each motor and a main controller of the device is configured to transmit a control command for each motor controller.
However, in the multi-axis machine and the multi-axis robot, when the motor and the motor controller are installed one to one, the number of motor controllers increases, and thus, manufacturing costs increase and an installation space of the motor controllers needs to be ensured and thus, it is difficult to downsize the device.
Accordingly, a technology of individually controlling several motors by one motor controller has been developed recently. For example, Korean Patent No. 10-0665059 (patent 1) and No. 10-0718232 (patent 2) disclose a technology of branching a plurality of inverters (motor drivers) supplying power to each motor from one power supply source and controlling the plurality of inverters (motor drivers) by one motor controller, respectively.
However, when several motors are controlled by one motor controller, it is necessary to accurately control the operation of each motor in real time. Particularly, in the case of installing a separate motor for each drive wheel, such as an independent-drive electric vehicle, casualties may occur when a malfunction occurs, and thus, high control reliability is required.
The patent 1 and 2 above disclosed technology of enhancing control reliability by preventing noise due to interference between the inverters. However, by only the technology, it is difficult to implement a target speed stably under a severe condition in which an operation load is changed in real time and control to exhibit stable torque over a wide speed range.
Accordingly, in a field of an independent-drive electric vehicle, a multi-axis precision machine, and a multi-axis robot that simultaneously drive several motors to perform specific operations, it is necessary to develop a more precise control technique capable of exhibiting a stable torque over a range while controlling several motors by a single motor controller.
Meanwhile, researchers or developers of electric vehicles, multi-axis robots, multi-axis machine tools, and the like test the speed and torque of the motor while varying the control parameters of the motor controller during research and development. But, there are many difficulties in modifying or adding the control parameters, because most of the researchers are not familiar with the program installed on the motor controller,
In particular, since the control program installed in the motor controller corresponds to the trade secret of the manufacturer, in most cases, the control parameters are set by the manufacturer according to the request of the user. As a result, it is practically impossible to test the performance of the motor in various fields while variously changing the control parameters.
Therefore, there is a need to develop a motor controller that allows motor users or related researchers to more easily set or add the control parameters.

Motor control device controlling several motors independently


Provided is a gas switch triggered by an optical pulse introduced by an optical fiber, which solves the problem of the existing electrically-triggered gas switch and laser-triggered gas having a complicated trigger system, being insufficiently reliable and having a higher cost due to the pulse amplitude/laser beam energy having higher requirements. The gas switch triggered by an optical pulse introduced by an optical fiber includes at least one trigger gap and one self-breakdown gap; each trigger gap is connected in parallel to a photoconductive switch, and an optical fiber is correspondingly provided for introducing an optical pulse for triggering. In the present disclosure, the advantages of a low trigger requirement of a photoconductive switch and a high voltage and large conduction current of a gas switch are fully utilized, and an optical pulse introduced by an optical fiber is used to trigger the photoconductive switch, so that the gas switch can be controlled and triggered under the action of a low-energy optical pulse (which can be less than 200 μJ) transmitted by optical fiber, thereby greatly simplifying the scale and complexity of the trigger system and promoting the development and application of the pulse power supply technology.

A switch is one of the core devices of a pulse power device, and its performance directly affects output characteristics of the device. A gas switch is a switch device in which one or more gaps are formed between a plurality of electrodes, and gas filled in the one or more gaps are utilized to achieve high voltage on-off. The gap which is directly turned on under an action of an external trigger pulse is a trigger gap, and other gap is a self-breakdown gap. A gas switch has various advantages, such as a high working voltage, a large conduction current, fast trigger response, low trigger jitter and a low cost, and thus is widely used in the technical field of pulse power and high voltage electrical engineering.
At present, gas switches are usually triggered by high-amplitude electric pulses. Taking a ±100 kV multi-gap gas switch used in a Fast Linear Transformer Driver (FLTD) as an example (Jiang Xiaofeng, Sun Fengju, Liang TianXue, et al. Experimental Study on Breakdown Characteristics of a Multi-gap Gas Switch [J]. High Voltage Technology, 2009 (01):103-107), the gas switch is a 6-gap gas switch. In order to ensure that the switch trigger jitter is less than 5 ns, an amplitude of the trigger pulse is required to be greater than 140 kV. Due to a high requirement of a gas switch on the amplitude of an electric trigger pulse, the trigger system is complicated and huge, and introduction of a trigger cable is difficult, which has become a main limiting factor in application of the FLTD technology.
A high energy laser pulse can also be used to trigger a gas switch. Taking a 200 kV multi-gap switch triggered by laser as an example (Li Hongtao, Wang Yujuan, Xia Minghe, et al. Study on the Trigger delay and Jitter of Laser-triggered Multi-stage Switch [J]. High Voltage Technology, 2006 (02):48-50), the gas switch is formed by a 10 mm laser trigger gap and 9 stages of 1 mm overvoltage self-breakdown gaps, and is directly triggered by a laser beam. The required trigger laser energy is more than 15 mJ, and the laser wavelength is 266 nm. However, due to the extremely complex optical path when being triggered by a laser beam, and a high requirement on environment and a high cost of the optical path system, 200 kV gas switches are rarely directly triggered by high-energy laser beams at present.
The existing gas switches have high requirements on the amplitude of an electric trigger pulse and the energy of a laser trigger pulse, thereby limiting application of gas switches in pulse power devices.

Gas switch triggered by optical pulse introduced by optical fiber

NORTHWEST INSTITUTE OF NUCLEAR TECHNOLOGY