Abstract: A simple and efficient single mixed refrigerant process for cooling and liquefying a hydrocarbon feed stream, such as natural gas. The process employs a closed-loop single mixed refrigerant process for refrigeration duty. The refrigerant compressed to a high pressure using at least three stages of compression and two intercoolers (both producing liquid). A hydraulic turbine is used to expand the high pressure refrigerant before it flows into the main heat exchanger.

Abstract: A headset includes a speaker, such as a side firing dipole speaker. The headset includes a front chamber that receives sound waves from a first side of the speaker and a rear chamber that receives sound waves from a second side of the speaker. A control leak channel connects the front chamber and the rear chamber. An acoustic mesh may be located within the control leak channel. The speaker configuration is configured to reduce total harmonic distortion of the speaker, particularly in ranges such as 3-6 kHz, while maintaining the broadband efficiency of the speaker.

Abstract: A method of generating a focused shock wave with a handheld focused extracorporeal shock wave therapy (f-ESWT) device includes driving a plurality of piezoelectric elements to generate a focused shock wave based on a first plurality of time delays when a first standoff structure is removably connected to a handheld housing of the f-ESWT device, and driving the plurality of piezoelectric elements to generate the focused shock wave based on a second plurality of time delays when a second standoff structure is removably connected to the handheld housing of the f-ESWT device, the second plurality of time delays different from the first plurality of time delays, and the second standoff structure different from the first standoff structure.

Abstract: A headset includes a speaker, such as a side firing dipole speaker. The headset includes a front chamber that receives sound waves from a first side of the speaker and a rear chamber that receives sound waves from a second side of the speaker. A control leak channel connects the front chamber and the rear chamber. An acoustic mesh may be located within the control leak channel. The speaker configuration is configured to reduce total harmonic distortion of the speaker, particularly in ranges such as 3-6 kHz, while maintaining the broadband efficiency of the speaker.

Abstract: Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Abstract: Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Abstract: This invention relates to the field of firearms, and in particular to a bipod for supporting a firearm, particularly high-calibre weapons. A bipod for supporting a bipod for supporting a firearm having a barrel, the bipod comprising: two legs rotatably mounted at respective opposing ends of a yoke and moveable between folded, intermediate, and firing positions, an elongate support member extending rearwardly of the yoke, and attachment means for attaching the bipod to the firearm in which the elongate support member is fixed to the yoke, and the attachment means is pivotally mounted on the elongate support number to permit canting of the firearm about a longitudinal axis.

Abstract: A disclosed data acquisition system includes one or more streamers having multiple spaced apart sensor units. At least one sensor unit includes at least one digital sensor employing a quantized feedback loop to produce a digital output signal. A data recording system collects and stores data from the sensor units. The quantized feedback loop may be adapted to exert a quantized force on the sensing element. A described method for acquiring data includes deploying at least one streamer having multiple spaced apart sensor units, where at least a portion of the sensor units include a digital sensor employing a quantized feedback loop to produce a digital output signal. A stimulus event is triggered. Data is received from the sensor units and stored.

Abstract: Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Abstract: Geophysical sensor cables. At least some of the example embodiments are sensor cable sections including hydrophone groups defined along a geophysical sensor cable section, the hydrophone group may include: a substrate of flexible material having electrical traces thereon, the substrate within the internal volume or embedded within the outer jacket, and the substrate having has a length measured parallel to the longitudinal axis; and a plurality of hydrophones mechanically coupled to the substrate. The substrate may have a variety of shapes, including one or more strips, helix, double helix, and cylindrical.

Abstract: Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A modeling module is included and configured to calculate a reference potential at a selected electrode for each of the plurality of geophysical survey cables, as well as a calculation module to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to the reference potential.

Abstract: An enhanced anaerobic adhesive composition containing microencapsulated metal ions is disclosed. Microencapsulated metal ions, such as iron oxide, copper naphthenate, cobalt naphthenate, ferrocene, and ferrocene derivatives, act as bonding sites in the composition, such that the composition achieves more complete polymerizations in a shorter curing time. The curing properties and the cure quality are significantly improved by the inclusion of microencapsulated metal ions. The composition can be used to bond metal and plastic substrates.

Abstract: A merged particle velocity signal is generated by merging a recorded vertical particle velocity signal, scaled in an upper frequency range using a time-dependent arrival angle as determined by velocity analysis, with a simulated particle velocity signal, calculated in a lower frequency range from a recorded pressure signal using a time-varying filter based on the time-dependent arrival time. Combined pressure and vertical particle velocity signals are generated by combining the recorded pressure and merged velocity signals.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential.

Abstract: A disclosed pressure-responsive sensor includes a flexible element contained within an enclosure and a membrane configured to exert an electrostatic force on the flexible element to cause the flexible element to respond to pressure variations on the membrane. A disclosed pressure-sensing method includes electrostatically coupling a membrane to a flexible element contained within an enclosure to transfer a pressure response of the membrane to the flexible element. Motion of the flexible element is converted into a pressure signal.

Abstract: A passive sound pressure level (SPL) limiter is provided that can be used with audio sources of varying drive levels and headphones or earphones of varying sensitivity. The SPL limiter includes a control circuit and left and right channel limiting circuits, each of which includes a pair of FETS. The SPL limiter may include a balancing circuit that separates the control signal output by the control circuit into left and right channel control signals. The SPL limiter may also include a microphone, for example integrated into an earpiece cable.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A modeling module is included and configured to calculate a reference potential at a selected electrode for each of the plurality of geophysical survey cables, as well as a calculation module to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to the reference potential.