Abstract: A method of preparing selenium nanoparticles (NPs) using an edible mushroom extract. In an embodiment, the edible mushroom extract is derived from the species Pleurotus floridanus. In an embodiment, the method includes combining a mushroom extract with a source of selenium to provide an extract mixture, and maintaining the mixture at a pre-determined temperature until the selenium nanoparticles are formed. These nanoparticles can be used for antimicrobial purposes.

Abstract: A method of preparing selenium nanoparticles (NPs) using an edible mushroom extract. In an embodiment, the edible mushroom extract is derived from the species Pleurotus floridanus. In an embodiment, the method includes combining a mushroom extract with a source of selenium to provide an extract mixture, and maintaining the mixture at a pre-determined temperature until the selenium nanoparticles are formed. These nanoparticles can be used for antimicrobial purposes.

Abstract: A method of preparing selenium nanoparticles (NPs) using an edible mushroom extract. In an embodiment, the edible mushroom extract is derived from the species Pleurotus floridanus. In an embodiment, the method includes combining a mushroom extract with a source of selenium to provide an extract mixture, and maintaining the mixture at a pre-determined temperature until the selenium nanoparticles are formed. These nanoparticles can be used for antimicrobial purposes.

Abstract: A method includes lifting a first plunger within a production string disposed within a wellbore. The production string divides the production string into multiple stages. The plunger landing assemblies include a first landing assembly and an intermediate landing assembly. The lifting includes lifting the first plunger in a first stage to lift production fluid accumulated uphole of the first plunger. The method also includes continuing to lift the first plunger until the first plunger strikes the intermediate one of the plurality of landing assemblies, allowing the production fluid to flow past the second one of the plurality of landing assemblies into a second stage. The method also includes securing the first plunger and lifting, with the production fluid accumulated uphole of a second plunger residing in the second stage, the second plunger to lift the production fluid toward the wellhead.

Abstract: Implementations of the present disclosure include a wellbore assembly that includes a wellhead assembly and a plunger. The wellhead assembly is coupled to a wellbore string disposed within a wellbore. The wellhead assembly includes a lubricator, a spring, and a flexible damper. The lubricator defines a tubular housing. The spring is disposed at least partially within and attached to the tubular housing. The spring comprises a first end attached to the tubular housing. The flexible damper is coupled to a second end of the spring opposite the first end. The plunger strikes, as the plunger is lifted from a downhole location of the wellbore to the terranean surface, the flexible damper. The flexible damper deforms, upon impact with the plunger, to dissipate some or all of the kinetic energy of the plunger.

Abstract: There is described a system comprising an outer conduit; an inner conduit positioned within the outer conduit such that an annular space is defined between the outer conduit and the inner conduit; and a resistive heating material occupying at least a portion of an annular volume within the annular space and having a positive temperature coefficient of resistance.

Abstract: A system generates augmented reality content by generating an occlusion mask via implicit depth estimation. The system receives input image(s) of a real-world environment captured by a camera assembly. The system generates a feature map from the input image(s), wherein the feature map comprises abstract features representing depth of object(s) in the real-world environment. The system generates an occlusion mask from the feature map and a depth map for the virtual object. The depth map for the virtual object indicates a depth of each pixel of the virtual object. The occlusion mask indicates pixel(s) of the virtual object that are occluded by an object in the real-world environment. The system generates the composite image based on a first input image at a current timestamp, the virtual object, and the occlusion mask. The composite image may then displayed on an electronic display.

Abstract: A depth estimation module may receive a reference image and a set of source images of an environment. The depth module may receive image features of the reference image and the set of source images. The depth module may generate a 4D feature volume that includes the image features and metadata associated with the reference image and set of source images. The image features and the metadata may be arranged in the feature volume based on relative pose distances between the reference image and the set of source images. The depth module may reduce the 4D feature volume to generate a 3D cost volume. The depth module may apply a depth estimation model to the 3D cost volume and data based on the reference image to generate a two dimensional (2D) depth map for the reference image.

Abstract: A transformerless parallel active rectifier system includes N multiphase common mode inductors directly connected to a shared multiphase AC input with no intervening transformer, and N active rectifiers coupled to respective ones of the N multiphase common mode inductors and having respective DC outputs coupled to a shared DC bus, where N is an integer greater than 1. The N active rectifiers have ground current regulators and are synchronized to provide DPWM switching control signals synchronized to one another to regulate their respective ground currents and concurrently regulate the shared DC bus voltage.

Abstract: For Direct Current (DC) bus voltage control, a method generates a q-axis reference current from a DC voltage error that includes a DC voltage input modified by a DC bus voltage in a closed outer loop. The method further generates a d-axis reference current from the DC voltage error, wherein the second-order harmonic in the d-axis reference current is delayed from that in q-axis reference current by 90 degrees. The method generates a q-axis current from the q-axis reference current. The method generates a d-axis current from the d-axis reference current. The second-order harmonic in d-axis current is offset from the second-order harmonic in q-axis current by 90 degrees. The method controls the DC bus voltage of a voltage control plant to mitigate a second-order harmonic in the DC bus voltage with the second-order harmonics in the q-axis current and the d-axis current.

Abstract: For Direct Current (DC) bus voltage control, a method generates a q-axis reference current from a DC voltage error that includes a DC voltage input modified by a DC bus voltage in a closed outer loop. The method further generates a d-axis reference current from the DC voltage error, wherein the second-order harmonic in the d-axis reference current is delayed from that in q-axis reference current by 90 degrees. The method generates a q-axis current from the q-axis reference current. The method generates a d-axis current from the d-axis reference current. The second-order harmonic in d-axis current is offset from the second-order harmonic in q-axis current by 90 degrees. The method controls the DC bus voltage of a voltage control plant to mitigate a second-order harmonic in the DC bus voltage with the second-order harmonics in the q-axis current and the d-axis current.

Abstract: A component includes an adaptive estimator. A converter includes a switching rectifier connected to an LCL filter with a converter inductor, a capacitor, and grid inductor connected to a voltage source through a conductor with unknown inductance. Current of the converter inductor is input to the adaptive estimator which includes an ideal LCL filter model that generates, using a simple filter, a desired dynamic behavior of the converter and LCL filter and a disturbance compensator. An LCL steady-state (“SS”) compensation models a steady-state effect of the LCL filter and conductor. Output of the adaptive estimator is subtracted from output of the LCL SS compensation to form a disturbance estimate, which is summed with a feedback loop output of the converter to form a voltage control signal that controls switching of the switching rectifier. The voltage control signal is summed with the disturbance estimate and is input to the adaptive estimator.

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: A power converter having a dynamic bus controller to control a rectifier DC output for motoring and regenerating power flow directions, in which the controller controls a DC bus voltage between first and second regenerating voltage limits and limits power at the DC output in an increasing fashion with increasing values of the DC bus voltage according to a regenerating power limit parameter for a regenerating direction of power flow at a DC output. For a motoring direction of power flow at the DC output, the controller controls the DC bus voltage at the DC output between first and second motoring voltage limits and limits the power at the DC output in a decreasing fashion with increasing values of the DC bus voltage according to a motoring power limit parameter.

Abstract: For grid-connected power converter control, a method estimates a d-axis grid voltage from a d-axis reference current modified with a d-axis current and a q-axis current modified with a filter inductive reactance. The method generates a q-axis current error from a direct current (DC) voltage input and a DC bus voltage. The method estimates an observer q-axis grid voltage from a q-axis voltage output. The q-axis grid voltage observer estimates the q-axis grid voltage in a direct/quadrature (dq) reference frame equivalent to an ABC to DQ reference frame transform. The method determines a d-axis voltage output as a function of a d-axis current error and a q-axis current modified with a filter inductive reactance. The method determines a q-axis voltage output as a sum of the q-axis current controller output and the observer q-axis grid voltage.

Abstract: There is described a system comprising an outer conduit; an inner conduit positioned within the outer conduit such that an annular space is defined between the outer conduit and the inner conduit; and a resistive heating material occupying at least a portion of an annular volume within the annular space and having a positive temperature coefficient of resistance.

Abstract: A power converter having a dynamic bus controller to control a rectifier DC output for motoring and regenerating power flow directions, in which the controller controls a DC bus voltage between first and second regenerating voltage limits and limits power at the DC output in an increasing fashion with increasing values of the DC bus voltage according to a regenerating power limit parameter for a regenerating direction of power flow at a DC output. For a motoring direction of power flow at the DC output, the controller controls the DC bus voltage at the DC output between first and second motoring voltage limits and limits the power at the DC output in a decreasing fashion with increasing values of the DC bus voltage according to a motoring power limit parameter.

Abstract: For grid-connected power converter control, a method estimates a d-axis grid voltage from a d-axis reference current modified with a d-axis current and a q-axis current modified with a filter inductive reactance. The method generates a q-axis current error from a direct current (DC) voltage input and a DC bus voltage. The method estimates an observer q-axis grid voltage from a q-axis voltage output. The q-axis grid voltage observer estimates the q-axis grid voltage in a direct/quadrature (dq) reference frame equivalent to an ABC to DQ reference frame transform. The method determines a d-axis voltage output as a function of a d-axis current error and a q-axis current modified with a filter inductive reactance. The method determines a q-axis voltage output as a sum of the q-axis current controller output and the observer q-axis grid voltage.

Abstract: For grid-connected power converter control, a method estimates a d-axis grid voltage from a d-axis reference current modified with a d-axis current, and a q-axis current modified with a filter inductive reactance. The method generates a q-axis grid voltage from a direct current (DC) voltage input modified with the DC bus voltage modified with a notch filter to balance the voltage input and further reduced with the q-axis current. The method modifies the estimated d-axis grid voltage and the q-axis grid voltage by selectively removing second-order harmonics. The method further determines a d-axis voltage output and a q-axis voltage output as a function of the modified estimated d-axis grid voltage and the modified q-axis grid voltage.

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.