Abstract: A system may include a power converter and a control system communicatively coupled to the power converter. The control system may determine a first DC voltage associated with the DC bus based on one or more DC external capacitance values that correspond to one or more loads coupled to the power converter. The control system may also determine a second DC voltage associated with the DC bus based on a capacitance of a system in which the power converter operates. The control system may also determine a third DC voltage associated with the DC bus based on the first DC voltage and the second DC voltage and adjust an operation of the power converter based on the third DC voltage.

Abstract: The disclosure relates to a method for the measurement of relative air humidity in a fresh air induction tube of an internal combustion engine. Here a concentration of oxygen in the fresh air induction tube is measured by an oxygen sensor and a temperature in the fresh air induction tube is determined. The relative air humidity is determined depending on the measured concentration of oxygen and the determined temperature.

Abstract: The present application relates to methods and systems for mitigating condensate banking. In some embodiments, the methods and systems involve altering the wettability of a rock formation in the vicinity of a wellbore for a gas condensate reservoir.

Abstract: An active rectifier with a controller including a feedforward component, a modulator and a modulation index controller. The modulator generates switching control signals according to a reference to convert AC input power from the AC input to control the DC bus voltage at the DC output. The feedforward component computes the reference according to an estimated total inductance of the AC input, a grid voltage of the AC input, a modulation index reference, and a reactive power offset signal, and the modulation index controller computes the reactive power offset signal according to an error between the modulation index reference and a feedback modulation index.

Abstract: A stabilized emulsified acid composition for deep carbonate formation stimulation is provided. The stabilized acid emulsion composition includes a petroleum operable to provide a barrier between an acid and a reservoir rock, the acid operable to react with the reservoir rock to dissolve the reservoir rock and produce a wormhole, a functional framework operable to stabilize the stabilized acid emulsion, an emulsifier operable to stabilize the stabilized acid emulsion, and a corrosion inhibitor operable to provide protection against corrosion for the metal components of a well. The petroleum can be diesel. The acid can be hydrochloric acid. The functional framework can be selected from the group comprising surface-modified clay-based material, zeolites, hybrid organic-inorganic materials, covalent-organic framework materials, and boron nitride nanotubes, and combinations thereof. The functional framework can be a surface-modified clay material selected from an organoclay.

Abstract: A current regulator for a motor controller reduces distortion of the current output to a motor. Feedback signals corresponding to the current present on the motor are transformed into a fundamental and a harmonic reference frame. Notch filters in each reference frame attenuate components of the current feedback signal from the other reference frame. Current regulators in each reference frame receive the filtered current feedback signal in the corresponding reference frame and generate an output signal that is used to regulate the output current to the motor to the desired level of current in the corresponding reference frame. The output signal from the regulator in the harmonic reference frame is transformed to the fundamental reference frame, and the output of the two regulators are combined in a common reference frame to generate a reference signal corresponding to the required voltage output to the motor to achieve desired operation.

Abstract: Methods for producing proppants with a nanocomposite proppant coating are provided. The methods include coating the proppant particles with a nano-reinforcing agent, a surface modifier, and a resin to produce proppants with nanocomposite proppant coating. Additionally, a proppant comprising a proppant particle and a nanocomposite proppant coating is provided. The nanocomposite proppant coating includes a nano-reinforcing agent, a surface modifier, and a resin. The nanocomposite proppant coating coats the proppant particle. Additionally, a method for increasing a rate of hydrocarbon production from a subsurface formation through the use of the proppants is provided.

Abstract: The present application relates to methods and systems for mitigating condensate banking. In some embodiments, the methods and systems involve altering the wettability of a rock formation in the vicinity of a wellbore for a gas condensate reservoir.

Abstract: A stabilized emulsified acid composition for deep carbonate formation stimulation is provided. The stabilized acid emulsion composition includes a petroleum operable to provide a barrier between an acid and a reservoir rock, the acid operable to react with the reservoir rock to dissolve the reservoir rock and produce a wormhole, a functional framework operable to stabilize the stabilized acid emulsion, an emulsifier operable to stabilize the stabilized acid emulsion, and a corrosion inhibitor operable to provide protection against corrosion for the metal components of a well. The petroleum can be diesel. The acid can be hydrochloric acid. The functional framework can be selected from the group comprising surface-modified clay-based material, zeolites, hybrid organic-inorganic materials, covalent-organic framework materials, and boron nitride nanotubes, and combinations thereof. The functional framework can be a surface-modified clay material selected from an organoclay.

Abstract: Power converters, controllers, methods and non-transitory computer readable mediums are presented, in which a processor operates a switching rectifier in a first mode to regulate a DC bus voltage signal using rectifier switching control for motoring rectifier operation when the measured DC bus voltage value is less than or equal to a first threshold value, operates the switching rectifier in a second mode to regulate the DC bus voltage signal using rectifier switching control for regenerative rectifier operation when the measured DC bus voltage value is greater than the first threshold value and less than or equal to a higher second threshold value, and operates an inverter in a third mode to regulate the DC bus voltage signal using inverter acceleration/deceleration control when the measured DC bus voltage value is greater than the second threshold value.

Abstract: A system and methods for operating four in-line cylinders with common rail injection is described that comprises operating a first cylinder group without a compression and power stroke injection, but with an exhaust stroke injection while operating a second cylinder group with at least a compression stroke injection. In this way, the unburned fuel injected during the exhaust stroke enriches the exhaust-gas flow and further allows heating of the exhaust aftertreatment system. In one example provided, the first cylinder group is further configured to operate in an exhaust heating mode while also operating in a power generating mode.

Abstract: System, apparatus and methods are provided for identifying a phase loss condition in a motor drive. In one example, a power conversion system includes an active rectifier, a switching inverter, and a controller. The controller is operative to generate rectifier switching control signals to operate the rectifier, measure AC input voltage signals and determine grid current signals. If the rectifier circuit is not in a switching mode, the controller identifies a suspected AC input phase loss condition if two of the AC input voltage signals are in phase with one another. If the rectifier is in the switching mode, the controller identifies a suspected AC input phase loss condition if the absolute value of the sum of two of the grid current signals is less than a predetermined non-zero threshold.

Abstract: The present application relates to methods and systems for mitigating condensate banking. In some embodiments, the methods and systems involve altering the wettability of a rock formation in the vicinity of a wellbore for a gas condensate reservoir.

Abstract: The present application describes compositions and methods for the controlled delivery of acid to a desired location, for instance to a subterranean formation.

Abstract: For voltage angle control, a control module generates a control signal for a grid. A canceling function generates an output voltage angle as a function of the control signal that regulates the grid. The output voltage signal includes an angular canceling function that cancels an angular control portion of a dynamic response of the grid such that the control signal controls the grid as a second-order quadrant-axis current.

Abstract: The present application describes compositions and methods for the controlled delivery of acid to a desired location, for instance to a subterranean formation.

Abstract: Disclosed examples include power conversion systems, computer readable mediums and methods for mitigating input filter resonance, in which a controller operates an active front end (AFE) rectifier in a first mode to turn a single rectifier switching device on and off and measures a filter voltage or current signal while all of the rectifier switches are off. The controller determines a resonant frequency based on a transient response of the measured voltage or current signal, and selectively adjusts a rectifier control parameter to mitigate filter resonance based on the resonant frequency.

Abstract: Embodiments of a particle sensor are provided. In one example, a particle sensor for an exhaust system comprises at least two inlet openings for an exhaust-gas flow of the exhaust system, wherein the inlet openings are of different sizes, and at least two sensor elements, wherein in each case one sensor element is arranged downstream of one inlet opening. In this way, the relative proportion of different-sized particles within the exhaust-gas flow may be determined.

Abstract: A method of fracturing a reservoir comprising the steps of pumping a geopolymer precursor fluid through a wellbore into the reservoir at a fracture pressure, the geopolymer precursor fluid at the fracture pressure generates fractures in the reservoir, wherein the geopolymer precursor fluid is comprised of an amount of aluminosilicate, an amount of alkaline reagent, and a permeability enhancer, allowing the geopolymer precursor fluid to fill the fractures in the reservoir, shutting-in the wellbore at a wellbore pressure, the wellbore pressure maintains the geopolymer precursor fluid in the fractures, allowing the geopolymer precursor fluid to harden for a hardening time to form a geopolymer in the fractures, the geopolymer has a geopolymer matrix, the geopolymer matrix has a permeability, the geopolymer has a compressive strength, and reducing the wellbore pressure allows a reservoir fluid to flow from the reservoir through the geopolymer matrix of the geopolymer to the wellbore.

Abstract: Power conversion systems and methods are provided for ride through of abnormal grid conditions or disturbances, in which a system rectifier is operated in a first mode to regulate a DC voltage of an intermediate DC circuit, an inverter is operated in the first mode to convert DC power from the intermediate DC circuit to provide AC output power to drive a load. In response to detecting an abnormal grid condition, the system changes to a second mode in which the rectifier is turned off and the inverter regulates the DC voltage of the intermediate DC circuit using power from the load.