174results about How to "Reduce additional loss" patented technology

The invention discloses a bend-insensitive radiation-resistant single-mode fiber and relates to the field of a single-mode fiber. The single-mode fiber comprises a core layer, an inner wrapping layer and an outer wrapping layer, which are arranged in sequence from the inside out. The core layer, the inner wrapping layer and the outer wrapping layer are made of quartz material. The inner wrapping layer comprises a first fluorine-doped inner wrapping layer and a second fluorine-doped inner wrapping layer arranged in sequence from the inside out. The core layer and the first fluorine-doped inner wrapping layer are germanium-undoped, and other metal impurities and phosphorus concentration are lower than 0.1 ppm; in mass percent, the doped fluorine content in the core layer is 0-0.45%, and chlorine content is 0.01%-0.10 %; fluorine content in the first fluorine-doped inner wrapping layer is 1.00%-1.55%; and the fluorine content in the second fluorine-doped inner wrapping layer is 3.03%-5.00%. Compared with an existing radiation-resistant single-mode fiber, additional loss of the single-mode fiber under a bending state is greatly reduced, and bending-resistant performance thereof is better, that is, the single-mode fiber is insensitive to bend; and meanwhile, the radiation-resistant capability of the single-mode fiber is better.

The invention discloses a manufacturing process for an optical fiber coupler, which includes: firstly, respectively grinding two optical fibers; secondly, combining two grinded surfaces; fusing the grinded surfaces by a high-temperature heating source; and finally, precisely controlling the splitting ratio of the coupler by the process of continuous fusing or biconical taper. The manufacturing process can be used for manufacturing a high-performance polarization maintaining optical fiber coupler, a single-mode optical fiber coupler, a multi-mode optical fiber coupler and a multi-mode coupler with a splitting ratio unrelated to an input wavelength and an activation pattern, the polarization maintaining optical fiber coupler and the single-mode optical fiber coupler manufactured by the manufacturing process have the advantages of short coupled area, high reliability, fine temperature property, polarization independence, wavelength independence and the like, and the multi-mode optical fiber coupler manufactured by the manufacturing process has quite high reliability besides quite low added loss.

The invention relates to a dynamo using slot wedge using compound soft magnetic powder magnetic conductance material. The powder is the compound soft magnetic powder compounded from MnZn ferrite powder and reduced iron powder or carbonyl iron dust. The radio is 10-90wt% high resistivity magnetic powder, and 10-90wt% high magnetic permeability magnetic powder. Adding certain quantity glass fiber into compounded magnetic powder layer, separating structure would be formed. The invention could decrease supplementary load loss of dynamo, as well as eddy current loss, and improve efficiency of dynamo.

This invention relates to a control rod drive circuit of a nuclear power plant reactor characterizing that said drive circuit applies a double topological structure of an adjustable circuit loop parameter, the electronic switches S1, S2 of the upper and lower arms of the circuit are serial to a connection resistor R< x > and a RC-absorption protection circuit RCD, S1 and S2 are connected to the middle point and R< x >, the RCD is connected with a quick successive current diode D after connecting to the middle point then to a DC power Ud and the D is parallel to the R and L of the coil, in which, the coil supply device of the rod-control system has very good drive and following ability for the rising and falling of current, very small stress of electronic switch and additive loss to control circuit.

The invention discloses an implementation method of automatic resonance type electric power filtering and continuous reactive power compensation. When a resistant of an automatic resonance type electric power filtering and continuous reactive power compensation mixing system is designed, a medium voltage side winding equivalent impedance of a rectification transformer is equal to or approximately equal to 0, meanwhile the equivalent impedance under h harmonic frequency is equal to or approximately equal to 0 under the control of a multiple target mixture controller. By using the method, the restriction to an electric power filtering function by system impedance is eliminated, the influence caused by frequency fluctuations at an electric network side and a nonlinear load side to the electric power filtering performance can be avoided, and the high-efficiency operation of a power supply system is realized.

The invention discloses an automatic deflection-keeping optical fiber coupler fusion cone-stretching device, which comprises the following parts: working bench, automatic shaft-shoot system on the working bench, medium approximate system, fusion cone-stretching system, on-line packaging system and main control computer, wherein the left and right symmetrical distribution mechanic platforms and control panel are set on the working bench; the automatic shaft-shoot system contains four groups of the same structure electric rotary system, light source and microscopic image system with four groups of diagonal shape electric rotary system on the left and right mechanic platforms as well as light source and microscopic image system on the working bench; the medium approximate system is set on the central line position of left and right mechanic platforms; the fusion cone-stretching system contains heat source and motion cone-stretching system; the left and right mechanic platforms are fixed on the motion cone-stretching system separately.

The invention discloses a control method for high-power reactive and harmonic dynamic hybrid compensation method. The hybrid compensation system comprises an SVG (static var generator), a TSF (thyristor switched filter) group and a controller, and the SVG and TSFs are parallelly connected to a grid. The three-phase current of the grid between the SVG and the TSFs is taken as a detection object, voltage and current values collected by sensors are processed through the controller, switching signals of the TSFs are acquired according to hybrid logic judgment, most of the reactive power of loads is compensated in a graded manner, and specific subharmonic is filtered out; control parameters of the SVG are acquired according to an instantaneous-power theory, and the surplus reactive power and harmonic of the loads are continuously compensated. A cost-effective scheme for rapid continuous compensation of the high-power reactive and harmonic is provided, impact of switching of passive equipment on the grid can be completely avoided, and harmonic current is avoided flowing to the grid, so that the control method is energy saving, emission reducing, green, environment friendly, good in social and economical effectiveness, wide in application range and especially applicable to the field of oil drilling.

The invention discloses a power collection and transmission system for a wind power plant. The system comprises an alternating current generatrix, a wind generating set, a rectifier station and an inverter station, wherein the rectifier station comprises a rectifier and a converter transformer; the direct current side of the rectifier is connected with the direct current side of the inverter station, and the alternating current side of the rectifier is connected with one side of the converter transformer through a converter inductor; and the other side of the converter transformer is connected with the alternating current generatrix, and is grounded through a capacitor. The invention also discloses a voltage control method for the alternating current generatrix of the system. The voltage comprising the amplitude and frequency of the voltage of the alternating current generatrix of the system is integrally controlled by two control dimensions of the rectifier on a wind power plant side, so that the stability of the alternating current voltage of the power collection and transmission system of the wind power plant is ensured, and harmonic components of an alternating current system of the wind power plant are reduced.

The invention discloses a low-loss large-effective area single mode fiber and a manufacturing method of the low-loss large-effective area single mode fiber, and relates to the field of optical fibers. The low-loss large-effective area single mode fiber comprises a quartz glass cladding, an internal coating and an external coating, wherein the quartz glass cladding, the internal coating and the external coating are arranged in sequence from inside to outside; the inside of the quartz glass cladding comprises a first fiber core area, a second fiber core area, a third fiber core area, a fourth fiber core area and a refractive index concave cladding, wherein the first fiber core area, the second fiber core area, the third fiber core area, the fourth fiber core area and the refractive index concave cladding are arranged in sequence from inside to outside; the refractive index concave cladding is subjected to deposition through a PCVD process; the quartz glass cladding is manufactured through an OVD process or a sleeving process. According to the low-loss large-effective area single mode fiber and the manufacturing method of the low-loss large-effective area single mode fiber, the scattering loss of the low-loss large-effective area single mode fiber and the additional loss of the low-loss large-effective area single mode fiber in a bent state can be reduced; due to the fact that the spire distribution of fiber core basic mode electromagnetic field power is adjusted into flattop distribution, optical power density is reduced, the effective area of the low-loss large-effective area single mode fiber is enlarged, the nonlinearity of the low-loss large-effective area single mode fiber is reduced, the incident power of an optical fiber communication system is increased by 0.4-2.6 dB, and the low-loss large-effective area single mode fiber is suitable for mass production.

Disclosed is an optical fiber cabin-penetrating sealing connection socket device used for a sealing cabin. The device comprises sealing flanges, optical fiber sealing seats, optical fibers, inner-side dockingplug cores and outer-side docking plug cores, the sealing flanges and the sealing cabin are sealed by adopting welding sealing or sealing rings, each sealing flange is provided with at least one optical fiber sealing seat mounting hole, the optical fiber seats are fixed in the mounting holes through laser welding sealing, the middle of each optical fiber is fixed in a central micropore of the corresponding optical fiber sealing seat through low-temperature glass welding material sealing, each of the inner-side and outer-side docking plug cores is fixed in the mounting holes at two ends of corresponding optical fiber sealing seat through interference fit, two ends of each optical fiber are bonded and fixed with the inner-side and outer-side docking plug cores respectively through epoxy glue, PC type or APC type docking faces are formed through fine grinding processing, and two ends of each sealing flange are connected with corresponding plugs in a matched manner respectively by adopting connection modes like thread connection or bayonet connection for optical signal transmission. The optical fiber cabin-penetrating sealing connection socket device used for the sealing cabin is compact in structure, effective in sealing, simple in method and low in cost, and optical signal transmission between inside and outside of the sealing cabin is effectively realized.

The invention relates to a mechatronic alternating current (ac) motor stator core of a compressor and a wire embedding method thereof and especially relates to an ac motor stator core of a piston refrigeration compressor used in a refrigerator. The motor stator core comprises an iron core body. A rotor aperture is arranged in a middle part of the iron core body. Wire embedding slots, which penetrate along an axial direction, are arranged along a circumferential direction of a hole wall of the rotor aperture. Inner sides of the wire embedding slots are provided with notches. A circumferential width (chord length) Bs0 of the notch is 0.1-1.0 mm. By using the stator core and the method of the invention, iron core surface losses and tooth pulse vibration losses can be reduced; an air gap coefficient is decreased; a field current is reduced; a power factor is raised so that working efficiency of the motor can be raised. Through redesigning a slot type size of the wire embedding slot, the additional losses generated by a harmonic field can be reduced so that the working efficiency of the motor can be further raised. A computer simulation experiment shows that the working efficiency of the motor can be increased by 1.5% by using the stator core of the invention. The stator core and the method is especially suitable for the single-phase asynchronous ac motor used in the totally enclosed refrigeration compressor.

The invention discloses a three-phase two-pulse-wave high-power pulse current power supply for electrolytic cells and a power supplying method. The three-phase two-pulse-wave high-power pulse current power supply for the electrolytic cells comprises a three-phase voltage regulation transformer, a three-phase induction filtering and rectifying transformer, a three-phase induction filter, a same-phase inverse-parallel-connection alternating current bus bar, single-phase rectifying cabinets, same-phase inverse-parallel-connection direct current bus bars and a unified controller. The three-phase voltage regulation transformer, the three-phase induction filtering and rectifying transformer and the same-phase inverse-parallel-connection alternating current bus bar are serially connected in sequence, output ends of the same-phase inverse-parallel-connection alternating current bus bar are respectively connected with input ends of the single-phase rectifying cabinets, output ends of the single-phase rectifying cabinets are connected with positive and negative electrodes of the electrolytic cells through the same-phase inverse-parallel-connection direct current bus bars, and the unified controller is connected with control ends of the single-phase rectifying cabinets. Two-pulse-wave high-power pulse current power source adjustable in duty ratio can be supplied to the electrolytic cells, thereby the electrolytic cells can be guaranteed in the most efficient electrolysis state and energy consumption of electrolysis is greatly reduced.

The coupling device of the present invention includes two pieces of proper fiber, fiber fixing block and fiber reinforcing block; spacer combination; LN waveguide chip; and package shell. The fiber with fiber fixing block and fiber reinforcing block is supported inside the package shell and has one end connected to side of the LN waveguide chip supported by spacer combination inside the shell andthe other end extending beyond the shell and as the input or output interface, with the joint to the shell being adhered. By means of improved coupling technology and structure, the light waveguide in the modulator is coupled with fiber precisely and reliably with high stability, low additional loss, low lkight reflection, and insertion loss not affected by temperature change and mechanical vibration.

The invention discloses a multi-section skewed pole rotor type permanent magnet wind-driven generator which comprises a stator and a rotor, wherein tile-shaped platy permanent magnet S poles and tile-shaped platy permanent magnet N poles are respectively embedded on the outer wall of the rotor. The concrete embedding and arranging processes are as follows: the transverse permanent magnet S poles and the transverse permanent magnet N poles are alternately arranged at intervals around the outer wall of the left section of the rotor, the permanent magnets with the same polarity are sequentially arranged along the axial direction of the rotor to form 3-18 sections, and the permanent magnets with the same polarity at the back section and the front section are in contact and are misaligned for an arc length of 0.1-1.0 permanent magnet along the rotation direction. A plurality of sections of permanent magnets which are arranged in a misaligned way form a rotor skewed pole structure. When rotating, the rotor is continuously and sequentially tangential with a magnetic line of the stator along the axial direction, and the moment of resistance in the starting stage is small, thus the rotor can rotate at lower wind speed to achieve the purpose of power generation. The fluctuation of the torque output by the rotor is small, thereby remarkably reducing the rotational vibration and the noiseof the wind-driven generator and improving the power generation quality simultaneously. The multi-section skewed pole rotor type permanent magnet wind-driven generator is suitable for being used as generators of different powers.

The invention discloses a photo-cured fluorine-containing organosilicone optical fiber coating and a preparation method thereof. The photo-cured fluorine-containing organosilicone optical fiber coating comprises the following active ingredients in parts by weight: 30-60 parts of polytrifluoropropylvinylmethylsiloxane and 5-30 parts of thiopropyl silicon oil, as well as photoinitiator the weight of which is 1-5wt% of the total weight of active ingredients. The preparation method of the coating comprises the following steps: preparing polytrifluoropropylvinylmethylsiloxane, thiopropyl silicon oil and the photoinitiator (the weight of which is 1-5wt% of the total weight of active ingredients) according to the formula, and evenly mixing to obtain the photo-cured fluorine-containing organosilicone optical fiber coating. Compared with the prior art, the photo-cured fluorine-containing organosilicone optical fiber coating has lower refractive index, and low additional losses, as well as higher mechanical strength.

The present invention discloses a four-stage iron core cast-aluminum rotor with a skewed slot structure. The number of slots of the rotor is the same as the number of slots of the stator; the rotor comprises a rotor iron core, a rotation shaft and a conducting bar; the rotation shaft is sleeved with the rotor iron core; the slot body of the iron core is in a skew shape, the conducting bar is casted in the slot body of the iron core; the iron core comprises a second iron core and a third iron core located at the middle position, and a first iron core and a fourth iron core which are respectively located at two ends; each two slot bodies having opposite positions of the first iron core, the second iron core, the third iron core and the fourth iron core are reversely skewed to be a herringbone shape; an intermedium ring is arranged between the second iron core and the third iron core; the two slot bodies having opposite positions of the second iron core and the third iron core are malposed and reversely skewed; and the bottom portions of the slot bodies are bifurcation structures. The present invention further discloses a stator matching the rotor and a motor. The four-stage iron core cast-aluminum rotor with a skewed slot structure, the stator and the motor effectively weaken tooth harmonic, reduce synchronous additional torque and reduce the additional loss of the motor.

The invention relates to the technical field of optical fiber communication and optical fiber sensing, and particularly to a polarization beam splitting and combining device. The polarization beam splitting and combining device comprises a first double-fiber polarization-maintaining optical fiber collimator, a first Wollaston prism, a third positive lens, a wave plate group, a fourth positive lens, a second Wollaston prism and a second double-fiber polarization-maintaining optical fiber collimator. The polarization beam splitting and combining device provided by the invention can split lights in any polarization state input to any port into two beams of linearly polarized lights and outputs the linearly polarized lights or on the contrary, so that the additional consumption is low, almost no absorption loss exists, the extinction ratio is very high, the volume is small and easy to integrate, the environmental stability is high, and great superiority is achieved in the aspect of performances, the material is easy to obtain, the economy is high, and the polarization beam splitting and combining device is widely applied to the field of optical fiber sensing, optical fiber communication, laser equipment, scientific research and the like.

A main-frequency resonance type electric induction boiler is composed of the induction heater consisting of vertically arranged multiple induction heating tubes, a capacitor, an upper boiler cylinder or upper water collecting tank above said induction heating tubes, and a lower water collecting tank under said induction heating tubers. Said induction heating tube comprises a water tube, an internal heating steel tube and an external electromagnetic induction coil. When said induction heating tube is electrically and parallelly connected with said capacitor, a parallel resonance takes place to save electric energy by 50%.

The invention discloses an all-optical fiber broadband flat intermediate-infrared super-continuum spectrum light source. The light source is characterized in that the light source comprises a thulium-doped mode-locked fiber laser module used for generating ultra-short pulses, a thulium-doped fiber amplification module used for generating high-power and high-order soliton pulses, a 2-3 micron high-power SC spectrum generation module used for generating 2-3 micron high-power SC spectrum laser, a silica fiber and chalcogenide fiber efficiently-coupled and encapsulated module and a 2-5 micron intermediate-infrared broadband flat SC spectrum generation module for generating a 10dB-bandwidth coverage 2-5 micron intermediate-infrared band broadband flat SC spectrum, wherein the thulium-doped mode-locked fiber laser module, the thulium-doped fiber amplification module, the 2-3 micron high-power SC spectrum generation module, the silica fiber and chalcogenide fiber efficiently-coupled and encapsulated module and the 2-5 micron intermediate-infrared broadband flat SC spectrum generation module are arranged sequentially. According to the light source, quartz optical fiber tapering and lens optical fibers are used in a matched manner, so that efficient coupling of quartz optical fibers and chalcogenide optical fibers can be realized, and pumping efficiency can be improved, the high-quality full-optical fiber broadband flat intermediate-infrared SC (super-continuum spectrum) light source can be realized; since the light source is of a full-optical fiber structure, the intermediate-infrared SC spectrum light source has the advantages of low cost, high conversion efficiency, high-quality output beams and simple and compact structure.

The invention relates to a kind of copper belt H class insulation dry-type hollow self-cooled flat wave electric reactor that comprises loop, insulation pressed board, stick, it characterized in that the loop is single-cake type, the inner brace is set in the inner layer of loop, the lead which enwinds the inner brace is bare copper belt, H class insulation duct bar is set between every circle of loop, H class insulation cushion block is set between nearby cakes, the loop is clamped by up and down insulation pressed board, and the H class insulation brace bar is set outside the loop, said inner and outer insulation brace bar, insulation duct bar, insulation cushion block adopts H class insulation material. The advantages are following: the structure is simple and reasonable, the electric property is good, the mechanical robustness is high, and radiation property is good, the temperature rise of loop is low, the volume is small, weight is light, the noise is low.

The invention discloses a high-resistance surface metamaterial waveguide slot antenna. The metamaterial waveguide slot antenna comprises a metamaterial waveguide tube and a radiation gap, wherein the metamaterial waveguide tube comprises a metal waveguide tube and a dielectric plate, the metal waveguide tube is a through tube with a rectangular cross section, the radiation gap is arranged in an upper surface of the metal waveguide tube, one end of the metal waveguide tube is opened and is used as a signal input port, the other end of the metal waveguide tube is closed and is in a short-circuit state, the dielectric plate is arranged on a wide edge of a lower part of an inner wall of the metal waveguide tube along a length direction, a periodic pattern is etched on a surface of the dielectric plate. By the antenna, low-loss radiation can be achieved in a working frequency band, and the antenna is high in efficiency; and by the antenna, dual-band suppression outside the working frequency band can be achieved, the characteristic of the antenna is equivalent to that of a high-pass filter when electromagnetic interference of a low frequency band is suppressed, and the characteristic of the antenna is equivalent to that of a band rejection filter when electromagnetic interference of a high frequency band is suppressed.

The invention discloses a soft switching boost DC-DC converter and a control method thereof and the soft switching boost DC-DC converter comprises filter capacitors of C1, C2, and C3, filter inductors of L1 and L2, switching elements of S1 and S2, diodes of D1, D2 and D3, a direct voltage detection circuit, a drive circuit and a controller, wherein the inductor L2, the capacitor C2, diode D2 and the switching element S2 form a buffer circuit. The switching element S1 is first started in each sampling period and the soft switching of the switching element S1 of a main power circuit is realized through an auxiliary buffer circuit. The converter in the invention does not need the extra placement of auxiliary elements besides the main power circuit when being applied, thereby effectively reducing the system consumption, volume and cost.

The invention relates to an ultralow-attenuation and large-effective-area single-mode fiber comprising a core layer and wrapping layers. The ultralow-attenuation and large-effective-area single-mode fiber is characterized in that the radius r1 of the core layer is 5-8 microns, the relative refractive index deltan1 of the core layer is 0-0.20%, and the core layer wraps an internal wrapping layer, a recessed internal wrapping layer and an external wrapping layer from inside to outside in turn. The radius r2 of the internal wrapping layer is 8.5-12 microns, and the relative refractive index deltan2 is -0.20--0.45%. The radius r3 of the recessed internal wrapping layer is 12.5-30 microns, and the relative refractive index deltan3 is -0.40--0.65%. The external wrapping layer is a fully fluoridated silicon dioxide glass layer, and the relative refractive index deltan4 is -0.22--0.53%. The ultralow-attenuation and large-effective-area single-mode fiber has the specific viscosity matching design: the core layer is not the pure silicon core and has the characteristics of co-doping of germanium and fluorine, and the chlorine doping technology is also performed so that the fiber viscosity can be reduced and the structural relaxation of glass can be accelerated; and the core layer viscosity matching is optimized by controlling the doping concentration, and the viscosity of each part of the fiber and the fiber strain are optimized so that ultralow-attenuation performance of the single-mode fiber can be realized.

The present invention discloses an integrated gate commutated thyristor. The said gate commutated thyristor includes n-type substrate, p-type doped region, n-type doped region, anodic p+ doped region of the gate commutated thyristor, diode n+ buffer region, and cathode paling of gate commutated thyristor, and also includes cathode and gate of the gate commutated thyristor, anode of the diode, anode of the gate commutated thyristor and cathode of the diode. The present invention has characters: n+-type isolating ring is set between the p-type doped regions of the gate of the gate commutated thyristor and the anode of the diode. The integrated gate commutated thyristor and its processing method can achieve effectively isolation between GCT element and the diode.

The invention discloses a double-skewed-slot rotor, which relates to the technical field of motors. A slot number of the rotor is equal to that of a stator matched with the rotor. The double-skewed-slot rotor comprises a first rotor and a second rotor; a slot body of the first rotor and a corresponding slot body in the second rotor are twisted in opposite directions; skewed slot distances of the first rotor and the second rotor are both as follows: (shown in the description); skewed slot angles of the first rotor and the second rotor are both as follows: (shown in the description); Z1 is a slot number of the stator, p is a number of pole pairs of a motor, and Di1 is an inner diameter of the stator; and a staggered angle of the slot body of the first rotor and the corresponding slot body in the second rotor is as follows: (shown in the description), wherein Z2 is a slot number of the rotor. The invention also discloses a stator-rotor equal-slot matching structure based on the rotor. The double-skewed-slot rotor has the advantage that the limitation on the selection of the slot number of the stator and rotor of a traditional induction electric motor and the application of the equal-slot matching can be broken through.

The invention discloses an energy-saving three-phase asynchronous motor of a special winding, comprising a stator winding which is embedded in a stator channel; the stator winding is an unequal-turn winding, with single-layer winding for whole distance and dual-layer winding for short distance; the turn of the upper layer and the lower layer of the coils of the dual-layer winding is unequal. By adopting the structure, the motor can weaken and eliminate the magnetic potential of high harmonic, reduces the electromagnetic noise, decreases the single-side magnetic pulling force, so as to reduce the vibration, can improve the magnetic potential of fundamental wave and reduce the additional loss; the reduction of the pitch leads the starting performance of the motor to be better, reduces the copper dosage, reduces the copper loss, lowers the temperature increment of the winding and improves the usage efficiency of the motor.

The invention relates to a seven-core small-diameter single mode fiber. The seven-core small-diameter single mode fiber comprises seven single-mode fibers having the same core cladding structure, wherein the seven fibers combined together closely, one fiber located at the center of the fibers, and the other six fibers surround the periphery of the center fiber; the single-mode fiber comprises a core layer and a cladding layer, the cladding layer comprises an inner cladding layer, a sunken cladding layer and an external cladding layer from the inside to the outside, radius r4 of the external cladding layer is 20-25 microns, ratio r4 / r1 of the radius of the external cladding layer to the radius of the core layer is 5.1-5.5, ratio r4 / r2 of the radius of the external cladding layer to the radius of the inner cladding layer is 2.4-2.8, and ratio r4 / r3 of the radius of the external cladding layer to the radius of the sunken cladding layer is 1.6-2.0. With the fiber provided by the invention,external diameter of the multi-core fiber is reduced greatly, and communication capacity density of unit cross section of the fiber is improved remarkably; consequently, space resource for paving pipelines is reduced; meanwhile, signal crosstalk influence among different fiber units is eliminated. The fiber provided by the invention has excellent comprehensive performance parameters, such as wavelength, mode field, attenuation and chromatic dispersion, in application wavebands, has microbending loss which is small enough. The fiber provided by the invention can be produced through a simple and convenient manufacturing method and needs low manufacturing cost.

The invention discloses a mine earthquake monitoring method based on fiber gratings. At least thirty coal sample test blocks are randomly selected from underground to-be-monitored area coal bodies, and change conditions of resonance wavelengths of the fiber gratings are obtained; multiple monitoring points are selected around the to-be-monitored area coal bodies to enable the monitoring points to surround a to-be-monitored area, multiple fiber grating sensors transmit real-time fiber grating resonance wavelength signals to an underground monitoring sub station through multi-core communication cables; the underground monitoring sub station transfers optical signals to a ground receiver; the change conditions of the resonance wavelengths of the fiber gratings of each monitoring point are obtained from the processed signals through a data processing computer; and a real-time comparison between change of the resonance wavelengths of the fiber gratings, monitored in real time and change rules of the resonance wavelengths of the fiber gratings, obtained through tests until comparison consistency occurs, and it is indicated that the coal bodies have the risk of mine earthquakes. The method provided by the invention is high in accuracy and good in real-time performance.

The invention relates to the field of motors and discloses a compressor and a permanent magnet motor thereof. The permanent magnet motor comprises a stator and a rotor, wherein the stator comprises a stator core and a stator winding; the stator core comprises multiple stator teeth, stator slots and a rotor containing part; the stator teeth are distributed in the peripheral direction of the stator at intervals; each stator slot is formed between two adjacent stator teeth; the rotor containing part is defined by inner end edges of the multiple stator teeth; the stator winding is arranged in the stator slots; the rotor can be rotationally arranged in the rotor containing part relative to the stator; the rotor comprises a rotor core; multiple magnet slots are formed in the rotor core in the peripheral direction at intervals; the rotor further comprises multiple magnetic parts which are respectively arranged in the multiple magnet slots; the distance between the rotation center of the rotor and an outer edge of the rotor containing part is Ris; the distance between the rotation center of the rotor and an outer edge of the rotor core is Ror; Ris-Ror is greater than or equal to 0.9 mm and less than or equal to 2.2 mm.

The invention discloses a method for splicing a photonic crystal fiber and a single-mode fiber. The method includes the steps that light curing adhesives permeate into the first end of the photonic crystal fiber, ultraviolet light is coupled into a fiber core of the photonic crystal fiber from the second end of the photonic crystal fiber, and the light curing adhesives at the portion, around the fiber core, in the first end of the photonic crystal fiber are cured to fill air holes of the photonic crystal fiber; the uncured light curing adhesives in the first end are removed, and the second end of the photonic crystal fiber is sealed; air pressure is applied to the first end of the photonic crystal fiber to allow the air pressure of air holes which are not filled to be higher than barometric pressure, the first end of the photonic crystal fiber is subjected to discharging heating to be at 1,400 DEG C to 1,900 DEG C, and the air holes which are not filled in the first end are collapsed and sealed; the first end of the photonic crystal fiber and the single-mode fiber are spliced. According to the method, the air holes in the photonic crystal fiber are subjected to selective area filling through the light curing materials in cooperation with the ultraviolet light, and therefore the technical problems that in the prior art, filling efficiency is low, and filling is uneven are solved.