摘要:
A method and apparatus for receiving video signals from a plurality of video cameras, such as in a video surveillance system. The video cameras are each coupled to provide a video signal to a respective input of a multiplexer. The multiplexer routes a selected one of the video signals to a video decoder. The video decoder receives the selected video signal and is conditioned according to the video signal. This includes synchronizing the video decoder to a frequency and phase of the video signal, controlling a gain level for the video signal and adjusting a dc clamping level for dc restoration of the video signal. Parameters representative of each of these quantities are stored in association with the identity of the corresponding video camera. The video decoder also places each video signal into a format suitable for storage in a storage device and for display by a display device. As the multiplexer is utilized to cycle through the cameras according to a sequence, the parameters for each camera are retrieved and utilized to initialize the video decoder for decoding the video signal received from the corresponding camera. As a result, the amount of time required to condition the video decoder according to the video signal received from each camera is significantly reduced. Accordingly, the present invention allows a surveillance system to cycle through a plurality of cameras in less time than prior systems having a single decoder, but without higher costs associated with prior systems which employ multiple video decoders.
摘要:
Methods of controlling fluid loss in a subterranean formation comprising: providing a treatment fluid comprising an aqueous fluid and a fluid loss control additive comprising a water-soluble polymer having hydrophobic or hydrophilic modification; introducing the treatment fluid into an interval of a well bore, the well bore penetrating the subterranean formation; creating one or more perforations in the interval of the well bore, wherein the perforations extend from the well bore and into the subterranean formation; and allowing the treatment fluid to contact a portion of the subterranean formation through the one or more perforations. Methods of a reducing fluid loss from a perforated and/or gravel packed interval of a well bore using a fluid loss control additive comprising a water-soluble polymer having hydrophobic or hydrophilic modification.
摘要:
A switching regulator provides programming output current control through a single input terminal by modifying the reference voltage in the control loop of the switching regulator. The switching regulator includes a first input terminal receiving a program input voltage indicative of a desired output current, a voltage divider receiving a first reference voltage and providing a second reference voltage at a first node between the first and second resistors and a third reference voltage at a second node between the second and third resistors, and a precision active pulldown circuit coupled to receive the program input voltage and operative to pull down the second reference voltage at the first node in response to the program input voltage. In operation, the third reference voltage is used in the control loop of the switching regulator to control the output current of the switching regulator in response to the program input voltage.
摘要:
In one embodiment, provided is a method of fracturing a portion of a subterranean formation that comprises providing a viscosified treatment fluid comprising a single salt aqueous fluid having a density of greater than 9 pounds per gallon and a crosslinked viscosifying agent, and contacting the portion of the subterranean formation with a viscosified treatment fluid so as to create or enhance one or more fractures therein, wherein the viscosified treatment fluid is introduced into a well bore that penetrates the portion of the subterranean formation to be fractured at a surface pressure of less than about 25,000 pounds per square inch. In other embodiments, provided are methods of frac packing a subterranean formation and methods of reducing a surface pressure needed to create one or more fractures in a portion of a subterranean formation.
摘要:
Methods of using invertible oil external-water internal emulsions in drilling, hydraulic fracturing, gravel packing and completion and then inverting the emulsion to a water external-oil internal emulsion are provided. The methods basically comprise the steps of contacting the oil external-water internal emulsion with an aqueous acid solution containing an anionic sulfonate surfactant for preventing aqueous acid solution-crude oil emulsions and crude oil sludging and a chemical for preventing the anionic sulfonate surfactant from reacting with the emulsifier in the oil external-water internal emulsion.
摘要:
A wide-band, high-order, programmable video filter is implemented using transimpedance-based active integrators. An input voltage which may for instance represent a composite video signal is converted to a current in a linear manner using resistors and provided to a current amplifier at low impedance virtual ground nodes. The current is multiplied by a gain factor .beta..sub.R within the current amplifier and supplied to integrating capacitors connected in a feedback configuration around a high input impedance differential amplifier to establish an integrated differential voltage output. The transimpedance-based active integrators may be interconnected to realize wide-band, high-order video filters suitable for use in accordance with CCIR 601 standards. Input voltage swings are not restricted by a transistor's limited range of linear operation or voltage swing limitations of internal nodes but rather may allowed to swing as long as the bias currents sustain input current excursions. Thus, pre-filter attenuation and post-filter amplification is not required, thereby allowing CCIR 601 standard compliant video filters to be fabricated, in accordance with the present invention, as a single chip IC.
摘要:
A wide band, high-order, programmable video filter is implemented using transimpedance-based active integrators. An input voltage which may for instance represent a composite video signal is converted to a current in a linear manner using resistors and provided to a current amplifier at low impedance virtual ground nodes. The current is multiplied by a gain factor .beta..sub.R within the current amplifier and supplied to integrating capacitors connected in a feedback configuration around a high input impedance differential amplifier to establish an integrated differential voltage output. The transimpedance-based active integrators may be interconnected to realize wide-band, high-order video filters suitable for use in accordance with CCIR 601 standards. Input voltage swings are not restricted by a transistor's limited range of linear operation or voltage swing limitations of internal nodes but rather may allowed to swing as long as the bias currents sustain input current excursions. Thus, pre-filter attenuation and post-filter amplification is not required, thereby allowing CCIR 601 standard compliant video filters to be fabricated, in accordance with the present invention, as a single chip IC.
摘要:
Provided herein are methods and systems that provide automatic compensation for frequency attenuation of a video signal transmitted over a cable. In accordance with an embodiment, a system includes an equalizer and a compensation controller. The equalizer receives a video signal that was transmitted over a cable, provides compensation for frequency attenuation that occurred during the transmission over the cable, and outputs a compensated video signal. The compensation controller automatically adjusts the compensation provided by the equalizer based on comparisons of one or more portions of the compensated video signal to one or more reference voltage levels. The compensating is selectively locked and reset in response to specific conditions being detected, e.g., a locking condition and a reset condition.
摘要:
Provided herein are methods and systems that provide automatic compensation for frequency attenuation of a video signal transmitted over a cable. In accordance with an embodiment, a system includes an equalizer and a compensation controller. The equalizer receives a video signal that was transmitted over a cable, provides compensation for frequency attenuation that occurred during the transmission over the cable, and outputs a compensated video signal. The compensation controller automatically adjusts the compensation provided by the equalizer based on comparisons of one or more portions of the compensated video signal to one or more reference voltage levels.
摘要:
Methods of reducing the permeability of a subterranean formation to aqueous-based fluids using a water-soluble relative permeability modifier that comprises a reaction product of a hydrophilic compound and a hydrophilic polymer. In some methods the hydrophilic polymer may be selected from the group consisting of: a polyacrylamide, a polyvinylamine, a poly(vinylamine/vinyl alcohol), an alkyl acrylate polymer, and a combination thereof. In other methods the hydrophilic polymer may be selected from the group consisting of: a polyvinylamine; a poly(vinylamine/vinyl alcohol); a cellulose; a chitosan; a polyamide; a polyetheramine; a polyethyleneimine; a polyhydroxyetheramine; a polylysine; a polysulfone; a gum; a starch, and a combination thereof.