35 results about "Ultrasound attenuation" patented technology

A noise-reducing attachment apparatus for a heat exchanger door is provided for facilitating attenuation of noise emanating from an electronics rack. The apparatus includes a frame structure configured to coupled to the heat exchanger door. The door includes in air opening and air-to-liquid heat exchanger, and air passing through the air opening also passes across the heat exchanger. The air opening facilitates passage of external air through the electronics rack. The frame structure defines in part an airflow channel through the apparatus, wherein air passing through the air opening also passes through the airflow channel when the apparatus is operatively coupled to the door. An acoustically absorptive material, which is coupled to the frame structure and at least partially defines the airflow opening through the apparatus, is selected and positioned to attenuate noise emanating from the electronics rack when the apparatus is coupled to the heat exchanger door.

Arrangements of X-ray inspection systems are described for inspecting high-z materials in voluminous objects such as containers. Inspection methods may involve generating a radiographic image based on detected attenuation corresponding to a pulsed beams of radiation transmitted through a voluminous object. The pulsed beams of radiation are generated by a high-energy source and transmitted substantially downward along an incident angle, of approximately 1° to 30°, to a vertical axis extending through the voluminous object. The generated radiographic image may be analyzed to detect on localized high attenuation representative of high-z materials and to discriminate high-z materials from lower and intermediate-z materials on the basis of the high density and greater attenuation of high-z material for higher energy (3-10 MeV) X-rays, and the compact nature of threatening masses of fissionable materials.

The invention discloses a multi-gain mode low-noise amplifier which comprises a high-gain channel mode, a low-gain channel mode, an attenuation channel mode and a switch for controlling the on/off mode switching of the multiple gain channels. By controlling the different gain channels, the invention realizes the high-gain, low-gain and attenuation modes in one circuit topology, realizes the high-gain, low-noise and high-linearity performance of the low-noise amplifier, and solves the problem that the circuit structure of any single mode can not simultaneously achieve optimal allocation effects in the aspects of gain, noise, linearity and other performance.

The attenuation system is applied to a compressor which comprises: a cylinder (2) having an end closed by a valve plate (4) provided with a discharge orifice (4a) and defining, with the cylinder (2), a compression chamber (6), a cylinder cover (5) being seated against the valve plate (4) and defining a discharge chamber (7), which communicates with the exterior of the compressor through a discharge tube (8). The attenuation system comprises: at least one intermediary chamber (10) defined in the interior of the discharge chamber (7), in order to receive, from the discharge orifice (4a), the whole discharge flow coming from the compression chamber (6); and at least one 4a connecting tube (20) mounted in the interior 4b of the discharge chamber (7), having a first end (21) open to the interior of the intermediary chamber (10) and a second end (22) open to the interior of the discharge chamber (7).

The invention discloses a method for testing optical attenuation of an LED light source, which comprises the following steps of fixing the LED light source at one end inside a hollow cylinder with a black inner surface, mounting an illuminometer probe corresponding to the LED light source in a corresponding position of the cylinder, reading an illuminance value; immobilizing the LED light source, reading an illuminance value at fixed intervals, reading for many times and recording each illuminance value; calculating optical attenuation according to data read in many times. The invention has the advantages that the illuminometer can read directly, thereby avoiding incorrectness of test result caused by the test instrument; the illuminometer can be read when lights are available, thereby solving the problem of metering distance; and the cylinder with the black inner surface avoids influence of parasitic lights; after mounting, the LED light source is not moved until result is tested, thereby reducing influences of the position and the angle of the light source, the artificial reading difference as well as improving the accuracy of test.

The instant disclosure relates to an apparatus, system and methods for determining the impact attenuation or hardness of a surface for a playground or sports field in order to mitigate or reduce sports and playground related injuries.

The present invention provides a multi-core cable in which skew occurs less and attenuation characteristics of all core cables are uniform, comprising: a core unit; an insulation tape spirally wrapped around the outer circumference of the core unit; and a metal coated resin tape wrapped over the insulation tape, wherein a plurality of core cables each consisting of two insulated wires arranged in parallel are stranded together to form the core unit, and wherein the metal coated resin tape is wrapped in the same direction as the stranding direction of the core cables.

The present invention relates to a simple method for determining high modulus asphalt fatigue performance. The method comprises: adopting a time scanning test to test plural shear moduli of high modulus asphalt under different loading times; and specifically adopting the loading time corresponding to attenuation of the plural shear moduli to 50% of the initial value at a temperature of 20 DEG C under frequency of 10 Hz, a strain of 1% (characterizes light traffic), a strain of 3% (characterizes moderate traffic) and a strain of 5% (characterizes heavy traffic) as a characteristic value of a high modulus asphalt fatigue performance simple test method. The test method has the following characteristics that: test data treatment is simple, special data analysis software is not required, high modulus asphalt fatigue performance simple test method application and promotion are easily achieved, the strain of the high modulus asphalt fatigue performance is 1-5% so as to carry out fatigue performance comparison on the high modulus asphalt under the same strain condition, and evaluation indexes are scientific and credible.

The invention relates to an ultrasonic echo measuring method for two-phase flow phase volume fraction. The method is used for measuring process parameters of two-phase flow flowing through a pipeline to be measured, an ultrasonic sensor using a single ultrasonic probe is arranged at the bottom end of the pipeline to be measured and does not make contact with a medium to be measured, an ultrasonic signal generating and detecting unit is achieved on the same ultrasonic probe, and the transmitting and receiving states of the ultrasonic probe are switched through two single-pole double-throw switches; the switch combination can control collecting the time sequence of transmitting signals and echo signals at the same time; strong reflection generated when ultrasonic waves pass through a medium interface with huge acoustic impedance difference is used for obtaining the position of the two-phase flow interface, the ultrasonic intensity attenuation rate is combined, gas-liquid interface curvature is compensated, the accurate two-phase flow phase volume fraction is calculated, and the measurement accuracy can be promoted.

The invention provides a photovoltaic multi-connected air conditioner carrier communication coupled transmission method and carrier communication coupled transmission circuit. The first signal coupled access pin of a broadband carrier module is connected with the copper pipe of a photovoltaic multi-connected air conditioner through a first Y capacitor. The second signal coupled access pin of the broadband carrier module is connected with the positive end or the negative end of the DC power supply line of the photovoltaic multi-connected air conditioner through a second Y capacitor. The signal coupled access pins of the broadband carrier module are respectively connected with the copper pipe and the positive end or the negative end of the DC power supply line through the Y capacitors so that the problems of being high in signal transmission attenuation, liable to be interfered, instable in impedance and complex in branch in the prior art can be solved.

The invention belongs to the field of production and processing of an attenuation sheet, and specifically relates to a manufacturing method for a 1dB attenuation sheet with power of 2W; the manufacturing method comprises the following steps of designing an attenuation sheet pattern through HFSS software in a simulation manner; sputtering a resistor and an electrode layer on an aluminum oxide ceramic substrate; electroplating a thickened gold electrode; obtaining electrode and resistor patterns through photoetching; dividing the attenuation sheet by a grinding wheel into independent attenuation sheet units; adjusting input and output impedances by a thermal oxidation impedance adjusting method; and coating the input end and the output end of the attenuation sheet with conductive silver paste. By adoption of the attenuation sheet manufactured by the invention, the operating frequency can achieve 18GHz; the attenuation precision within the operating efficiency is 1dB plus or minus 0.4dB; the standing-wave ratio is less than or equal to 1.3; and the input and output impedances are 50 plus or minus 1 omega.

An apparatus (1) for measuring the transmission or attenuation of electromagnetic radiation through an object (6), said apparatus including an electromagnetic radiation emitter (2) and detector (3), characterised in that to perform transmission/attenuation measurements, the apparatus in configurable such that said emitter (2) is positioned immediately adjacent the surface of said object (6) and said detector (3) is positioned on an opposing side of the object (6) such that the detector (3) solely, or at least substantially receives electromagnetic radiation transmitted through the object (6) from the emitter (2).

The fluoroscopic examination system of quantitative gene augmentor is composed of the light source with the color filter, the two-way mirror positioned in front of the light source inclined 45 degrees, the 96 optical fiber bundle coaxial with the light source and the corresponding sample cells. Each optical fiber bundle is leaded in the pinhole in the bottom of the base in each sample cell. The excitation and the reception of fluorescence are realized directly on the wall of the reaction tube. Thus, the phenomena of the fluorescence scattering and the light intensity attenuation are eliminated. The invention raises the detection sensitivity and reduces the manufacturing cost so as to possess the application value.

The invention discloses an automatic power adjusting method in an optical fiber communication system. The attenuation value of an optical fiber in each cross section is acquired. According to acquired attenuation value of an optical fiber in each cross section, the gain of an optical amplifier or an attenuator of a relay node in a corresponding cross section is adjusted. The invention further discloses an automatic power adjusting device in the optical fiber communication system. According to the invention, the device automatically adjusts the gain of a power amplifier and the attenuator according to line attenuation; power changes, which are caused by optical fiber aging and other problems, of a receiving end are prevented; automatic control and real-time power adjustment are realized; and compared with manual adjustment, the method and the device have the advantages of great operability, low difficulty and small impact on a system.

The invention discloses a method for producing a ytterbium-doped lithium nickel cobalt manganese oxide material used for a lithium ion battery. The method comprises the following steps: a) weighing the raw materials according to stoichiometric ratio; b) adding absolute ethyl alcohol in the raw materials, performing ball milling and taking the materials out and drying the materials; c) adding acetate fibre, potassium chloride and sodium chloride in the raw materials obtained in the step 2) for mixing with molten salt and absolute ethyl alcohol, performing ball milling and drying the materials; and d) sintering the raw materials obtained in the step c), cooling the materials, washing the obtained powder, and drying to obtain the material. The ytterbium-doped lithium nickel cobalt manganese oxide material has higher discharge capacity and gram capacity; and has a hollow tube structure, through further processing, the tube wall is loosening so as to alleviate the volume expansion problem; inorganic filling material titanium dioxide in the acetate fibre is used, and is doped into crystal lattice of the ytterbium-doped lithium nickel cobalt manganese oxide material, so that stability of the ytterbium-doped lithium nickel cobalt manganese oxide material is improved, and the capacity attenuation problem of the lithium ion battery is improved.

The invention discloses a method and system for detecting the mechanical tolerance of a photovoltaic module. The method successively comprises: inspecting the appearance defect of the photovoltaic module according to a predetermined appearance inspection standard; testing the optical attenuation rate of the photovoltaic module, and detecting the output power of the photovoltaic module under a predetermined test condition when the optical attenuation rate is less than a predetermined attenuation threshold; subjecting the photovoltaic module to a mechanical tolerance test; inspecting the appearance defect of the photovoltaic module according to the appearance inspection standard; detecting the output power of the photovoltaic module under the predetermined test condition; and ending the mechanical tolerance test. The method and system provide a reliable analysis basis and a determination criterion for the use performance, the service life, and the failure period of the photovoltaic modules used by a shared bicycle under different severe mechanical usage conditions, so as to make up for the lack of the detection process of the photovoltaic module used by the shared bicycle.

Method for calibrating a vectorial network analyzer, with n measurement ports (n>2) and at least m measurement sites, where m>n+1 includes measurement of three different n-port reflection standards, connected between measurement ports in any desired order, and successive measurement of reflection and transmission parameters at different transmission standards, connected between two respective measurement ports, and computational determination of error coefficients and error-corrected scattering matrices [S_x] of the n-port standards. Reflection standards, Short and Open, are unknown, but physically identical at each n-fold one-port. Reflection standard, realized by wave terminations, is known, but can be different at each n-fold one-port. Transmission standards are measured at a transmission standard, having known length and attenuation at a two-port, and at unknown transmission standards, identical for incident and reflected waves at remaining two-ports, which can be connected. Unknown reflection and transmission values are determined computationally by the measurements.

The invention discloses a digital chromatographic system which is composed of a central control unit, a communication module, a digital conversion module and a chromatographic device. The chromatographic device is a full-automatic purification system, the chromatographic device comprises a UV detector, a membrane pump, a pressure detector, a flow detector, a pH and Conductivity detector, a liquidlevel detector and an automatic valve; the system is provided with an RS485 communication module, an RS232 module and a ProfibusDP remote module; the communication module is direct in digital communication with an instrument and reads or writes in related numerical values; the digital conversion module converts on-site common analog signals into digital signals and transmits the digital signals into a control unit through the digital communication technology; the control unit and the instrument are subjected to full-digital communication control, after digital communication is introduced, analog signal attenuation, analog signal interference, installing circuit complexity and other problems in the prior art are solved, and water solutions and solutions with large viscosity can be effectively distinguished through an IOLink sensor.

The invention belongs to the field of airborne navigation, and relates to a device for detecting the height measurement precision of a radio altimeter. An attenuator (6) receives a height signal of a radio altimeter transceiver (1) and carries out the attenuation. A delay line (7) carries out the time delay processing of the height signal of the attenuator (6), and transmits the signal after time delay to the radio altimeter transceiver (1). A dedicated tester (2) is connected with the radio altimeter transceiver (1), a multifunctional digital voltage meter (3), and 429 bus equipment (4). The multifunctional digital voltage meter (3) collects a voltage value of the radio altimeter transceiver (1) through the dedicated tester (2), wherein the voltage value is corresponding to one height value. The 429 bus equipment (4) collects a binary height value of the radio altimeter transceiver (1) through the dedicated tester (2), wherein the binary height value corresponding to one height value.

The invention discloses an eight-channel broadband mobile network signal transmitting circuit, which consists of four frequency band selection and suppression circuits, four level compensation circuits, and four large-range attenuation circuits to form four radio frequency channel modules, and also includes four differential conversions circuit, four frequency band selection control units, four level compensation control units, four large-range attenuation control units, a core control unit and an installation substrate. The input signal enters the input port of the frequency band selection and suppression circuit in the radio frequency module, the output port of the frequency band selection and suppression circuit is connected to the input port of the level compensation circuit, and the output port of the level compensation circuit is connected to the input port of the wide range attenuation circuit , the output port of the large-range attenuation circuit is connected with the input port of the differential conversion circuit, and finally the signals are output from the two ports of the differential conversion circuit.

The invention provides a nondestructive testing method and system for external field airplane surface honeycomb structure corrosion damage. The nondestructive testing method for external field airplane surface honeycomb structure corrosion damage comprises the following steps: step one, enabling a sensor support and an exciter support to be located in a same plane local coordinate system; step two, enabling the parallel edges of the sensor support to be parallel to the parallel edges of an area to be tested correspondingly; step three, enabling the parallel edges of the exciter support to be parallel to the parallel edges of the area to be tested correspondingly; step four, guaranteeing that the plane projections corresponding to the distances at which a sensor and an exciter move on the corresponding supports are the same point; step five, distinguishing the attenuation of vibration frequency; step six, establishing a frequency response function database; and step seven, judging the degree of the honeycomb structure corrosion damage. The degree of the honeycomb structure corrosion damage is judged by testing the attenuation of vibration wave frequency propagated along the longitudinal direction of a honeycomb.