52 results about "Voltage reversal" patented technology

Sensor circuits for the measurement of small variations in the value of a sensing capacitor. An alternating voltage excites the sensing capacitor a predetermined frequency whereby the voltage on the sensing capacitor reverses polarity. This voltage on the sensing capacitor is sampled each time the voltage reverses polarity. An accumulator accumulates the sampled charges from the sensing capacitor. An output signal that represents the charge in the charge accumulating means indicates the measured capacitance.

Radio frequency identification (RFID) devices may be used to monitor various operating parameters in fuel cells. For example, RFID devices may be used to monitor the voltage of individual cells in a fuel cell stack and thus to check for voltage reversal conditions during stack operation.

The invention discloses a system and method for detecting photovoltaic hot spot damage solar cell leak currents. The method includes the steps that the distribution condition of the reversal biasing leak currents is determined by testing the temperature change condition of solar cells under the reverse bias voltage; the cells are classified according to the reverse leak currents; meanwhile, distribution of the reverse leak currents of the solar cells is detected through infrared heat phase scanning, and the cells with the large local leak current density are selected. By means of the system and method, the solar cells with the large local leak currents are selected, and the excessively-high-temperature hot spot problem is solved under the voltage reversal biasing condition caused by current mismatching in the practical use of the solar cells.

Systems and methods for arc handling in plasma processing operations are disclosed. The method includes providing current with a power supply to a plasma load at a first voltage polarity and energizing an energy storage device so when it is energized, the energy storage device applies a reverse polarity voltage that has a magnitude that is as least as great as the first voltage polarity. When an arc is detected, power is applied from the energy storage device to the plasma load with a reverse polarity voltage that has a polarity that is opposite of the first voltage polarity, the application of the reverse polarity voltage to the plasma load decreases a level of the current that is provided to the plasma load.

An anode catalyst layer for a fuel cell is presented having first and second catalyst compositions and a hydrophobic binder. The first catalyst composition includes a noble metal, other than Ru, on a corrosion-resistant support material; the second catalyst composition contains a single-phase solid solution of a metal oxide containing Ru. The through-plane concentration of ionomer in the catalyst layer decreases as a function of distance from the membrane interface. Gas diffusion electrodes, catalyst-coated membranes, MEAs and fuel cells having the foregoing anode catalyst layer are also described.

The invention discloses an anti-lock method, which mainly comprises the following steps: an initial comparison value is measured by experiments; a vehicle acceleration speed an and the wheel speed of each wheel are detected in real time, and an analog signal is output; the wheel speed signal of each wheel is transformed into a corresponding acceleration speed signal, wherein, three or more than three acceleration speed signals are transmitted into a programmable control unit through an or gate and simultaneously an signal am with largest value that is acquired from the voltage reversal of the acceleration speed signal of each wheel is output; an and am are transformed into the signals with the same voltage, and the transformed signals are input into the programmable control unit after respectively transformed by A / D, the comparison of an and am is implemented by the programmable control unit, deciding whether to start an anti-lock system according to the comparison result, and correspondingly controlling the increasing and decreasing of brake frequency; the snub brake of wheels is implemented by an electromagnetic-valve-controlled brake implementation unit until a vehicle or a plane stop movement. The invention has simple operation steps, is convenient, economical and practical, and by implementing the continuous snub brake of wheels, the invention can accurately implement anti-lock function and has high security.

Use of a selectively conducting anode component in solid polymer electrolyte fuel cells can reduce the degradation associated with repeated startup and shutdown, but unfortunately can also adversely affect a cell's tolerance to voltage reversal. Use of a carbon sublayer in such cells can improve the tolerance to voltage reversal, but can adversely affect cell performance. However, employing an appropriate selection of selectively conducting material and carbon sublayer, in which the carbon sublayer is in contact with the side of the anode opposite the solid polymer electrolyte, can provide for cells that exhibit acceptable behaviour in every regard. A suitable selectively conducting material comprises platinum deposited on tin oxide.

An electrochemical fuel cell stack comprises a plurality of fuel cell assemblies, wherein, each fuel cell assembly comprises a cell compressed between a pair of flow field plates, a perimeter seal circumscribing the cell and interposed between the pair of flow field plates, and a first diode, having an aspect ratio greater than 10:1, positioned adjacent to, and outside of, the perimeter seal along a first edge of the cell and interposed between the pair of flow field plates.

In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel. In order to pass current, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode, particularly if the anode employs a carbon black supported catalyst. Such fuel cells can be made more tolerant to cell reversal by using higher catalyst loading or coverage on the anode catalyst support or a more oxidation resistant anode catalyst support, such as a more graphitic carbon or Ti4O7.

An electrochemical fuel cell stack comprises a plurality of fuel cell assemblies, wherein, each fuel cell assembly comprises a cell compressed between a pair of flow field plates, a perimeter seal circumscribing the cell and interposed between the pair of flow field plates, and a first diode, having an aspect ratio greater than 10:1, positioned adjacent to, and outside of, the perimeter seal along a first edge of the cell and interposed between the pair of flow field plates.

In solid polymer electrolyte fuel cells, an oxygen evolution reaction (OER) catalyst may be incorporated at the anode along with the primary hydrogen oxidation catalyst for purposes of tolerance to voltage reversal. Incorporating this OER catalyst in a layer at the interface between the anode's primary hydrogen oxidation anode catalyst and its gas diffusion layer can provide greatly improved tolerance to voltage reversal for a given amount of OER catalyst. Further, this improvement can be gained without sacrificing cell performance.

Formation properties in a vertical section of a wellbore are determined by considering the vertical section as consisting of one or more segments. Measurements are obtained with a directional resistivity tool at two or more measurement stations within each segment for which the complex 0th harmonic coefficients for the obtained measurements are non-trivially different from one another. For each such segment, the phase shift and attenuation are determined using the complex 0th harmonic coefficients obtained for that segment and an inversion is performed for the formation properties using the determined phase shift and attenuation for that segment. Formation properties for that segment may be output to a display or memory storage device. For certain segments, one or more gain factors may be obtained. The gain factors are used to correct the measured voltages for certain neighboring segments and the corrected voltages inverted to obtain anisotropy and formation structure.

Systems and methods for arc handling in plasma processing operations are disclosed. The method includes providing current with a power supply to a plasma load at a first voltage polarity and energizing an energy storage device so when it is energized, the energy storage device applies a reverse polarity voltage that has a magnitude that is as least as great as the first voltage polarity. When an arc is detected, power is applied from the energy storage device to the plasma load with a reverse polarity voltage that has a polarity that is opposite of the first voltage polarity, the application of the reverse polarity voltage to the plasma load decreases a level of the current that is provided to the plasma load.

The disclosed invention provides a bridge voltage inversion circuit for vacuum gauge and a pressure gauge sensor that includes the bridge voltage inversion circuit. The bridge voltage inversion circuit for a pressure gauge includes a reference capacitance, a sensor capacitance, and a transformer including a primary winding and a secondary winding that outputs a bridge voltage. The reference capacitor is connected to a first side of the secondary winding of the transformer, and the sensor capacitor is connected to a second side of the secondary winding of the transformer. The sensor capacitor senses and responds to a pressure, and a capacitance of the sensor capacitor is at a minimum when the pressure is at vacuum. The capacitance of the sensor capacitor at vacuum is less than a capacitance of the reference capacitor.