206results about How to "Small signal attenuation" patented technology

To provide a magnetic recording medium which undergoes little effect of thermal fluctuation and provides a high short wavelength output and C / N ratio when reproduction is conducted using MR head, the magnetic recording medium includes a non-magnetic layer having a non-magnetic powder dispersed in a binder provided on a support and a magnetic layer having a ferromagnetic powder dispersed in a binder provided on the non-magnetic layer, wherein the ferromagnetic powder comprises a hexagonal ferrite magnetic powder having an average diameter of from 10 to 35 nm and a coercive force of from 135 to 400 kA / m; the magnetic layer has a coercive force of from 135 to 440 kA / m; and a product of an anisotropic magnetic field of the magnetic layer and an average particle volume of the hexagonal ferrite magnetic powder is from 1.2×106 to 2.4×106 kA / m·nm3.

The invention relates to impulse response analytical test apparatus and method for detecting deformation of transformer winding, belonging to the technical field of transformer winding detection. The apparatus mainly comprises an impulse generator, a broadband digital oscilloscope, a computer, a high-voltage probe, a head end signal impedance matching device, a tail end signal impedance matching device and a screened coaxial cable. In the method, site test and analysis are carried out by using the apparatus. The invention has the advantages of high test sensitivity, rapid detection, strong capacity of resisting disturbance and flexible analytical method, and can detect slight deformation of the transformer winding and judge early potential faults effectively with high judging accuracy. The invention can be widely applied to the detection of the deformation of the transformer winding and the state overhauling.

The invention provides a liquid crystal phased array-based laser radar system, and relates to the technical field of laser phase control. By the liquid crystal phased array-based laser radar system, the problem that incident light and emergent light are separated by a light splitter in an existing light path and the light intensity loss can be caused by introduction of the light splitter so that the application of a beam deflection system is limited are solved. The liquid crystal phased array-based laser radar system comprises a central processing unit, a laser emission system and an echo receiving system, wherein the laser emission system comprises a laser A and an emission light path, the emission light path comprises a beam expansion collimation system A, a refined deflection system, aone fourth wave plate and a rough deflection system, the refined deflection system comprises a one second wave plate, a liquid crystal spatial light modulator (LCSLM) and a DSP controller, the rough deflection system comprises a liquid crystal polarization rotator, a liquid crystal spatial light modulator (LCPG) and a polarization grating controller, and the echo receiving system comprises a fieldprogrammable gate array (FPGA), an MPPC and a receiving light path. An oblique incidence mode is employed, an included angle between light irradiating the liquid crystal spatial light modulator and emergent light is increased, the light path is simplified, the system volume is reduced, the light intensity loss caused by the light splitter is also reduced, and the application range of the liquid crystal spatial light modulator is expanded.

The invention relates to a squeeze head used for a rock conventional triaxial test acoustic emission test and belongs to the technical field of geotechnical engineering. The squeeze head comprises an upper squeeze head and a lower squeeze head, wherein the upper squeeze head and the lower squeeze head are arranged on a rock message delivery system (MTS) conventional triaxial compression test machine. Round grooves are formed in the lower end face of the upper squeeze head and the upper end face of the lower squeeze head. Two perpendicular installation holes are symmetrically formed in the bottom of each round groove. Perpendicular conductor holes are formed in bottoms of the installation holes. Horizontal conductor holes are formed in side walls of the upper squeeze head and the lower squeeze head, and the perpendicular conductor holes are communicated with the horizontal conductor holes. Springs are arranged at the bottoms of the installation holes. Cover plates are arranged on the round grooves and shapes and sizes of the cover plates are identical to shapes and sizes of the round grooves. By means of the squeeze head used for the rock conventional triaxial acoustic emission test, attenuation and distortion of emission signals can be reduced to the maximum extent, the situation that an acoustic emission sensor is immersed in hydraulic oil is avoided, the acoustic emission test of high confining pressure can be carried out and the facture surface of rock can be positioned.

An electromagnetic compatibility testing system includes an anechoic chamber. The anechoic chamber includes a testing table, an antenna, an amplifier, and a receiver. A test sample is placed on the testing table. The antenna receives electromagnetic signals emitted by the test sample and transmits the electromagnetic signals to the amplifier via a coaxial cable. The receiver is connected to the amplifier via the coaxial cable analyzing the electromagnetic signals amplified by the amplifier.

The invention discloses a long-term monitoring apparatus for a soil pressure outside a duct piece of a shield tunnel. The long-term monitoring apparatus is composed of a fiber grating strain brick, a fiber grating temperature compensation block, a cable box, and an armored cable. The fiber grating strain brick consists of a measuring stone and a mortar layer coating the outside of the measuring stone; and four fiber gratings are arranged at each of three surfaces, being perpendicular to each other, of the measuring stone. The fiber grating temperature compensation block includes a hollow metallic cylinder and a temperature compensation stone arranged inside the metallic cylinder; the space between the temperature compensation stone and the metallic cylinder is filled with EVA foam; and four fiber gratings are arranged at each of three surfaces, being perpendicular to each other, of the temperature compensation stone. In addition, the invention also discloses a long-term monitoring method for a soil pressure outside a duct piece of a shield tunnel. Using the apparatus and method disclosed by the invention, the soil pressure monitoring error can be reduced; and the installation survival rate can be improved. Moreover, the apparatus and method have characteristics of good anti-electromagnetic-interference and corrosion-resistant performances and low signal attenuation; and the soil pressure outside a duct piece of a shield tunnel can be monitored accurately for long time.

The invention relates to a multilayer super-rapid magnetic resonance imaging method based on segmental excitation space-time coding and relates to the magnetic resonance imaging method. According to the method, an imaging object is divided into multiple segments, at an excitation stage, a 90-degree segment selection sinc pulse is utilized to select an imaging segment, in-segment protons are made to spin through a 180-degree linear frequency modulation pulse to acquire a secondary phase, and time-space coding for the spinning protons in the imaging segment is carried out; the secondary phase information is stored through a phase identical to the 90-degree segment selection pulse; a layer selection 90-degree sinc pulse is connected, decoding and sampling for the protons are carried out. Through designing the center frequency and the decoding sampling gradient of the layer selection pulse, the magnetic resonance data of multiple layers of the segment can be acquired, different imaging segments are selected through correcting the center frequency of the segment selection pulse, and the multilayer data of the whole imaging object is acquired through repeated operation, high resolution reconstruction for the acquired magnetic resonance data of each layer is sequentially carried out, and the multilayer high resolution magnetic resonance image is acquired.

Provided is a high-temperature-resistant low-loss compound insulation coaxial cable. The high-temperature-resistant low-loss compound insulation coaxial cable is characterized in that a solid or stranded inner metal conductor (1), a polytetrafluoroethylene micropore compound insulation layer (2), an outer conductor (3) and a sheath layer (4) are arranged from inside to outside in sequence, the solid or stranded inner metal conductor (1) longitudinally extends along the central axis of the cable, the outer conductor (3) is formed by knitting metal or is additionally provided with an inner shielding layer, the sheath layer (4) is made of FEP copolymer or low-smoke halogen-free flame retardant polyolefin, and the inner metal conductor (1) and the outer conductor (3) are separated by the polytetrafluoroethylene micropore compound insulation layer (2); the polytetrafluoroethylene micropore compound insulation layer (2) is made of modified polytetrafluoroethylene organic-inorganic nanocomposites filled with nano polyhedral oligomeric silsesquioxanes (POSS). According to the coaxial cable, the dielectric constant of the insulation layer of the cable is reduced. A traditional solid polytetrafluoroethylene insulation dielectric constant is reduced to 1.2-1.6 from 2.1 and is reduced by about 24 percent to 43 percent, and the signal attenuation of cable high-frequency communication is reduced.

The invention discloses a Goa (Gate Driver on Array) circuit, a Goa (Gate Driver on Array) circuit scanning method, a display panel and a display device. The objective of the invention is to solve the problem of obvious attenuation of output signals caused by excessive cascade connection of Goa units in a traditional Goa circuit. According to the Goa circuit, the signal output end of a Goa unit at the n-th row is connected with the signal input end of a Goa unit at the n+k-th row; the output end of the Goa unit at the n+k-th row is connected with the reset signal end of the Goa unit at the n-th row and the signal input end of a Goa unit at the n+2k-th row; the Goa circuit also comprises a gating unit; the gating unit is connected with Goa units from the first row to the k-th row; the gating unit controls the Goa circuit to output scanning signals sequentially from the first group of gate lines to the k-th group of gate lines; and in the x-th group, the GOA circuit outputs scanning signals sequentially from the x-th row to the m*k+x-th row. The Goa circuit, the Goa circuit scanning method, the display panel and the display device of the invention are mainly applied to the display field.

The invention discloses a light beam deflection control method based on a liquid crystal optical phased array, relates to the field of liquid crystal optical phased arrays, and aims to solve the problems of low beam pointing precision and low system tracking bandwidth existing in the prior art; a beam of linearly polarized light emitted by a laser passes through a beam expanding collimation systemand an emitting system to generate linearly polarized light; the linearly polarized light is subjected to diffuse reflection on an object to be measured after passing through a beam contracting and angle expanding system; a receiving system receives light signals reflected by the object to be measured in a diffuse reflection mode, and the light signals are converged to the light sensing surface of a CCD detector, and the difference value between the laser spot position and the center of the CCD detector is calculated; an oblique incidence type triangular measuring method is adopted to obtainan actual light beam deflection angle; the error of the actual light beam deflection angle and a set light beam deflection angle is transmitted to a fractional order PID controller, and a liquid crystal optical phased array driving circuit is controlled by the fractional order PID controller to input a proper voltage to the liquid crystal optical phased array, so that the liquid crystal optical phased array generates corresponding phase modulation, and accurate deflection of emergent light beams is realized.

The invention relates to an optical cable connector for an environment resistant neutral optical cable, mainly comprising a lock sleeve, a belt locating pin, a locating hole, a plug body for a first and a second optical fiber locating holes, a protective bobbin and two ceramic ferrules; the two ceramic ferrules are positioned in the first and the second optical fiber locating holes through a small pressure spring and a pressure spring sleeve; and the front end of any ceramic ferrule is provided with an optical fiber butt joint assembly. When the connectors of the invention are connected in pairs, the locating pin of a connector matches with the top position of the locating hole of the other connector, and the ceramic ferrule of one connector is connected with the ceramic ferrule of the other connector through the optical fiber butt joint assembly. The optical cable connector has the advantages of stability and firmness for splicing, precise for positioning, small signal attenuation, stable transmission, compact structure, convenience for mounting, dismounting and maintenance, resistance to environmental change, and long service life, thereby satisfying the commercial or military requirement of miniaturization, high performance and field use.

To provide a magnetic recording medium which undergoes little effect of thermal fluctuation and provides a high short wavelength output and C / N ratio when reproduction is conducted using MR head, the magnetic recording medium includes a non-magnetic layer having a non-magnetic powder dispersed in a binder provided on a support and a magnetic layer having a ferromagnetic powder dispersed in a binder provided on the non-magnetic layer, wherein the ferromagnetic powder comprises a hexagonal ferrite magnetic powder having an average diameter of from 10 to 35 nm and a coercive force of from 135 to 400 kA / m; the magnetic layer has a coercive force of from 135 to 440 kA / m; and a product of an anisotropic magnetic field of the magnetic layer and an average particle volume of the hexagonal ferrite magnetic powder is from 1.2×106 to 2.4×106 kA / m·nm3.

The invention discloses a roadbed settlement monitoring device based on a fiber Bragg grating. The roadbed settlement monitoring device based on the fiber Bragg grating comprises at least two fiber Bragg grating liquid level sensors mounted on a monitoring surface; each fiber Bragg grating liquid level sensor comprises a cylindrical shell, and the bottom of each shell is mounted on a base; a rectangular cantilever beam, a cylindrical floating block and antifreezing solution are arranged inside each shell; the upper side and the lower side of each rectangular cantilever beam are respectively embedded into a fiber Bragg grating sensor, each floating block is suspended in the corresponding antifreezing solution, and each floating block is hinged with the free end of the corresponding rectangular cantilever beam; and the fiber Bragg grating sensors are welded and in serial connection with an optical cable, the optical cable is connected with a fiber Bragg grating demodulation instrument, strains of the rectangular cantilever beams when liquid levels in the shells are changed are acquired by virtue of the fiber Bragg grating demoulation instrument, adjacent upper sections of the shellsof the fiber Bragg grating liquid level sensors are communicated via a breather pipe, adjacent lower sections of the shells of the fiber Bragg grating liquid level sensors are communicated via a liquid flowing-through pipe, so as to enable the rectangular cantilever beams to produce bending deformation, and the liquid flowing-through pipe is connected with an automatic liquid level controller.

The invention provides an AMOLED pixel driving circuit, a driving method and a display panel. The AMOLED pixel driving circuit comprises a first thin film transistor (T1), a second thin film transistor (T2), a third thin film transistor (T3), a fourth thin film transistor (T4), a fifth thin film transistor (T5), a sixth thin film transistor (T6), a storage capacitor (C) and an organic light emitting diode (OLED). The AMOLED pixel driving circuit only has a data signal writing and threshold voltage compensation stage (A1) and a light emitting stage (A2). According to the embodiment of the invention, the design of the pixel driving circuit with a 6T1C structure is adopted, compensation and AMOLED anode reset are completed at the same time through data signal writing, the driving time sequence is simplified, the load of a scanning signal line is reduced, the signal attenuation is reduced, and the high refresh rate of the AMOLED pixel driving circuit is further realized.

The invention discloses a detection apparatus having a rapid detection function for a transient surface wave of a hard surface. The detection apparatus comprises a detector coupled with a hard surface rapidly to carry out data collection and a rapid arrangement device for arranging the detector. The detector includes a pedestal, a sensor element installed inside the pedestal, a connecting socket arranged at the top of the pedestal, and a coupling antenna arranged at the bottom of the pedestal; and a spherical structure is formed at the bottom of the coupling antenna. The rapid arrangement device includes two triangular-pyramid supports, a cross bar erected between the two supports, and elastic pins installed on the cross bar; metal rings with suspenders are arranged on the elastic pins; and the suspenders and connecting rings arranged at the top of the detector are detachably connected. According to the invention, rapid coupling of the detector and the hard surface is realized; arrangement time of the detector is substantially saved; and the working efficiency and precision of transient surface wave detection of the hard surface are improved.

The embodiment of the invention provides an organic light-emitting display panel and a display device, relates to the technical field of display, and aims to effectively reduce the occupation of touchelectrode leads on the space of a frame area and facilitate the realization of a narrow frame. The organic light emitting display panel includes: a plurality of touch electrodes extending in a firstdirection and arranged in a second direction. The first leads correspond to the touch electrodes; the first lead is made of a transparent conductive material. The first leads and the touch electrodesare positioned on different layers. An insulating layer is arranged between the first leads and the film layer where the touch electrodes are located, in the direction perpendicular to the plane wherethe organic light-emitting display panel is located, the first leads and the corresponding touch electrodes are at least partially overlapped, and the first leads are electrically connected to the corresponding touch electrodes through via holes in the insulating layer. The plurality of first leads extend along the first direction and are arranged along the second direction.

The invention discloses an acquisition method and a system for a reference clock signal, wherein the method comprises the following steps of: receiving a GPRS (General Packet Radio Service) satellite signal by GPRS receiving equipment; generating a TOD signal and an IPPS signal, and converting the TOD signal and the IPPS signal with electrical signal forms into optical signal forms, and sending the TOD signal and the IPPS signal with optical signal forms to a reduction device through an optical fiber; receiving the TOD signal and the IPPS signal with optical signal forms by the reduction device, recovering the TOD signal and the IPPS signal with optical signal forms to be the TOD signal and the IPPS signal with electrical signal forms, and compensating the IPPS signal with an electrical signal form, and making the TOD signal with an electrical signal form and the compensated IPPS signal as the reference clock signal. Through the method and the system, an installation distance for a GPRS antenna can be enlarged, and quality for reception for the GPRS satellite signal can be guaranteed; moreover, cost for the optical fiber is cheap, and erection cost for the GPRS antenna can be favorably reduced.

The invention belongs to the technical field of high speed railway settlement monitoring, and discloses a high speed railway settlement monitoring system based on fiber bragg gratings. The high speedrailway settlement monitoring system is used for solving the problem that an existing high speed railway settlement monitoring system is low in accuracy. The high speed railway settlement monitoring system comprises at least two fiber bragg grating level gages installed on a monitoring face; and each fiber bragg grating level gage comprises a shell, wherein the bottom of the shell is installed ona base, an elastic convoluted diaphragm is installed in the shell, and the shell is divided by the elastic convoluted diaphragm into an upper liquid containing zone and a lower installing cavity, thelower end face of the elastic convoluted diaphragm is provided with two optical grating fixing columns, a pressure measuring optical grating is installed between the two optical grating fixing columns, a temperature measuring optical grating is further installed in the installing cavity, the temperature measuring optical grating and the pressure measuring optical grating are connected with a datacollecting system, and the data collecting system transmits collected data to a control center.

The invention relates to a multi-node electrical stimulation system and method. The system comprises a sending end and multiple electrical stimulation nodes worn on the parts, needing to be stimulated, of a human body. The sending end couples modulation electrical signals carrying node serial numbers and stimulation waveform parameters to human body communication channels through a sending electrode of the sending end according to the conduction characteristics of human body tissue. An integrated electrode of the electrical stimulation nodes is used for receiving the modulation electrical signals transmitted to the surface of the human body through the human body communication channels. The modulation electrical signals are processed through signal conditioning and demodulating, corresponding waveforms are selected through a microcontroller, corresponding electrical stimulation waveforms are output through the integrated electrode after boosting, and the corresponding parts of the human body are stimulated. The system is used for rehabilitation training of a patient with paralytic limbs caused by the reasons such as central nerve damage, the system carries out electrical stimulation on the corresponding parts of the limbs according to the transmission paths of electroneurographic signals when the limbs move, and therefore the rehabilitation of the moving function of the limbs of the patient is promoted.

The invention provides an antenna device with excellent penetrating performance. The antenna device includes a first radiator, a second radiator, a third radiator, and a dielectric substrate. The slotof the first radiator is configured to adjust the antenna impedance to achieve an effect of adjusting the resonance frequency. The dielectric substrate with a corresponding dielectric constant is arranged between the first radiator and the second radiator as required. The third radiator is used as a reflection plate, is located below the second radiator and increases the gain in the direction of0-degree angle. A low-dielectric-constant medium with a certain thickness is disposed directly above the first radiator. A feeding point is disposed on the first radiator. The second radiator is grounded. The antenna device has excellent penetrating performance, and can still smoothly transmit energy to the outside when buried in reinforced concrete.

To make an optical switch smaller, two frames are formed by etching in such manner that when they are stuck together to form a support member, an hexagonal opening appears. The end portions of a pair of fixed optical fibers are arranged in the bottom portions of a pair of opposing V-grooves provided in this hexagonal opening. A pair of movable optical fibers are fixed at the other end of the support member, and these movable optical fibers are arranged in such manner that their end faces are contiguous with the end faces of the pair of fixed optical fibers. A drive mechanism causes the end portions of this pair of vertically arranged movable optical fibers to move to the left or the right, come into contact with the walls of respective V-grooves, slide into the bottoms of the grooves, and thereby have their cores aligned with the cores of the fixed optical fibers. Alternatively, two parallel beams formed from silicon are formed on the inside of a single frame, a pair of mutually opposing projections are formed in approximately the middle portions of these beams, and the end portions of a pair of optical fibers are arranged in and in contact with V-grooves formed parallel to and on the opposing faces of this pair of projections.

The invention relates to an MOEMS vector hydrophone comprising a fiber (1), fiber collimators (2), a base (3), a silicon-based framework (4), a cantilever beam (5), and a micro cylinder (6). The cantilever beam (5) is erected at the center of the silicon-based framework (4) and is installed in the base (3). The fiber collimators (2) is installed in mounting holes (32) of the base (3); and the fiber collimators (2) and a corresponding platform (51) arranged on the cantilever beam (5) form an F-P cavity (16). The micro cylinder (6) is installed on the corresponding platform (51) at the cross-shaped intersection position of the cantilever beam (5). One end of the fiber (1) is connected with the fiber collimators (2) and the other end is connected to an external optical path demodulation device. According to the invention, acoustic-mechanical-optical conversion is carried out by the F-P cavity. With combination of the MEMS technology and the fiber sensing technology by the MOEMS technology, requirements of miniaturization, low power consumption, and electromagnetic interference prevention can be realized; and the front-side power-free state of the hydrophone as well as high-sensitivity high-resolution detection of a weak acoustic signal can be realized.

The present disclosure discloses an HDMI photoelectric composite cable. The HDMI photoelectric composite cable includes: a sheath, an optical fiber unit, a plurality of signal control wires, a ground wire and fillers. The optical fiber unit includes one or more optical fibers and an optical fiber sheath uniformly extruded on a periphery of the optical fibers. The signal control wire includes a metal wire and an insulating layer uniformly extruded on a periphery of the metal wire. The ground wire is a metal conductor. The fillers are arranged on peripheries of the optical fiber unit, the plurality of signal control wires and the ground wire. The optical fiber unit, the plurality of signal control wires, the ground wire, and the fillers arranged on the peripheries thereof are covered by the shielding layer, and the shielding layer is covered by the sheath.

The invention discloses a radio frequency coaxial connector, and relates to a radio frequency coaxial connector for connecting between a transmission cable and a printed circuit board. Aiming at the problem that the conventional similar radio frequency coaxial connector only has two contact points for electrical connection and too small elastic holding and seizing force. The radio frequency coaxial connector is characterized in that: annular protrusions are designed at the outer periphery of a rear neck of an inner conductor pin head; an inner conductor pin tail consists of two tail plates which are bent into arc shapes and matched up and down and of which the opening ends have duckbill shapes, and the cross sections of the two tail plates are matched crescents; a connecting sleeve is designed between the non-opening end of the inner conductor pin tail and the rear neck of the pin head; and an insulating inner sleeve is designed between the outer periphery of the inner conductor pin tail and an insulating sleeve, and is provided with annular protruding reinforcing ribs corresponding to the surface of the outer periphery of the middle part of the maximally spaced bent arc part of the two tail plates and corresponding to the end part of the connecting sleeve. Through trial, the radio frequency coaxial connector has the advantages of obviously reducing signal attenuation, having more reliability of elastic holding, reducing manufacturing cost, and reducing the consumption of copper alloy, gold and silver resources.

The invention discloses a power line carrier centralized meter reading system node belonging automatic confirmation method. Through building a confirmation channel with frequency lower than 10khz, a main node at a low voltage side of a low voltage transformer can receive confirmation signals sent by slave nodes belonging to the main node through the confirmation channel and can not receive confirmation signals sent by nodes which do not belong to the low voltage side of the low voltage transformer of the main node through the confirmation channel, a node belonging abnormal condition can be avoided, automatic node belonging confirmation in the centralized meter reading system can be realized, and the cost for manual field inspection and test is reduced.

The invention provides a novel hierarchical heterogeneous cross-network air quality real-time monitoring model which comprises an air quality terminal monitoring module, routing nodes, sink nodes, a 3G / 4G air quality monitoring terminal module based on a 3G / 4G wireless network communication technology, and a property data service center, wherein the property data service center is used for receiving, storing, processing and compositing air quality information. Air quality terminal monitoring modules based on the ZigBee wireless technology for fixed nodes form a local ZigBee network in an Ad-Hoc network manner; the 3G / 4G air quality monitoring terminal module based on the 3G / 4G wireless network communication technology in a dynamic monitoring area is directly communicated with a server through a 3G / 4G wireless network; the property data service center saves air quality information transmitted by the ZigBee network and the 3G / 4G network. An air quality sensor comprises a PM 2.5 sensor, an MQ 135 sensor and a temperature sensor. According to the novel hierarchical heterogeneous cross-network air quality real-time monitoring model, fixed buildings and fixed plane domains can be monitored in real time simultaneously, and air quality change situations of a certain areas can be dynamically monitored.

The invention discloses a central tube strip optical cable in a polygon arrangement, comprising a fiber ribbon group in the center and a loose tube which wraps the fiber ribbon group; the fiber ribbon group is formed by the superposition of a plurality of fiber ribbons and every fiber ribbon is formed by parallel combination of a plurality of fibers; the number of the fibers of every fiber ribbon decreases gradually from the inside to the outside; the fiber ribbon which is positioned on the inner layer and has the largest number of fibers has at least two layers; the number of the fiber of the fiber ribbon which is positioned in the outer layer and has the smallest number of fibers is two; after superposition of fiber ribbons, the section of the fiber ribbon group is a polygon. In the optical cable, the fibers at the edge or the corner are stressed uniformly and the distance from the tube wall is widened, thereby reducing signal weakening and improving service performance.

The invention discloses a fiber bragg grating pressure sensor capable of achieving positive and negative pressure monitoring and a testing method. The fiber bragg grating pressure sensor comprises a connector, a filter screen, a base, an outer shell, a corrugate pipe, a first fiber bragg grating, a second fiber bragg grating, an optical fiber, an optical cable connector, an armored optical cable, a brace, a flange plate, an outer shell cover and a strain beam, wherein the outer shell cover is used for protecting the optical fiber from a sealing glue sealing part to an optical cable connector part, and the strain beam is used for applying prestress. The fiber bragg grating pressure sensor capable of achieving the positive and negative pressure monitoring and the testing method are suitable for the monitoring of pressure safety of oil and gas pipelines, urban underground gas pipelines, heating power pipelines, water supplying pipelines, oil tank pipelines, oil conveying pipelines and other pipe networks, the potential safety hazards that an electronic sensor is electrified and is unsafe in nature are eliminated, and meanwhile the capacity of phases is also improved greatly; the fiber bragg grating pressure sensor is applied to the aspect of real-time online monitoring of coal and rock mass gas pressure, errors caused by single data monitoring are avoided, the sensitivity and the accuracy of the system are improved, manpower, material resources and time are saved, and meanwhile the danger probably brought by personnel on site can be avoided.

A radio frequency transmission system for a magnetic resonance system includes a radio frequency power amplifier (40) generating an input radio frequency signal that excites magnetic resonance in target nuclei and is designed for feeding an impedance Zo, a multi-channel radio frequency coil (18) having N radio frequency channels where N>1, and a power splitter (44) including (i) a parallel radio frequency connection point (50) at which the N channels of the radio frequency coil are connected in parallel to define an output impedance at the parallel radio frequency connection point, and (ii) an impedance matching circuit (54) connecting the radio frequency power amplifier with the radio frequency connection point and configured to provide impedance matching between the radio frequency power amplifier and the output impedance at the connection point.

The invention provides a crack double-waveguide antenna which is characterized in that the crack double-waveguide antenna comprises two waveguide tubes which are fixedly connected through any two sides and are respectively used for transmitting electromagnetic wave signals of different frequencies, and crack sets which are arranged on two adjacent sides of the two waveguide tubes and include a first set of cracks arranged on one side and a second set of cracks arranged on the other side, wherein the polarization direction of the first set of cracks is parallel to the length direction of the waveguide tubes, and the polarization direction of the second set of cracks is perpendicular to the length direction of the waveguide tubes. Because of a high degree of isolation between crack double-waveguide antennas, the channel correlation of signals can approach 0 when the signals are transmitted or receiving using the crack double-waveguide antennas. Therefore, the crack double-waveguide antenna of the invention has the advantages of small signal attenuation and strong anti-interference capability. In addition, the crack double-waveguide antenna can well support the MIMO technology and save space resources.